Payload-Release Device Position Tracking

ABSTRACT

An unmanned aerial vehicle (UAV) is disclosed that includes a retractable payload delivery system. The payload delivery system can lower a payload to the ground using a delivery device that secures the payload during descent and releases the payload upon reaching the ground. The location of the delivery device can be determined as it is lowered to the ground using image tracking. The UAV can include an imaging system that captures image data of the suspended delivery device and identifies image coordinates of the delivery device, and the image coordinates can then be mapped to a location. The UAV may also be configured to account for any deviations from a planned path of descent in real time to effect accurate delivery locations of released payloads.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 14/584,189, filed Dec. 29, 2014, which claims priority to U.S.Provisional Patent Application No. 62/043,397, filed Aug. 28, 2014, bothof which are incorporated herein by reference in their entirety and forall purposes.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

An unmanned vehicle, which may also be referred to as an autonomousvehicle, is a vehicle capable of travel without a physically-presenthuman operator. An unmanned vehicle may operate in a remote-controlmode, in an autonomous mode, or in a partially autonomous mode.

When an unmanned vehicle operates in a remote-control mode, a pilot ordriver that is at a remote location can control the unmanned vehicle viacommands that are sent to the unmanned vehicle via a wireless link. Whenthe unmanned vehicle operates in autonomous mode, the unmanned vehicletypically moves based on pre-programmed navigation waypoints, dynamicautomation systems, or a combination of these. Further, some unmannedvehicles can operate in both a remote-control mode and an autonomousmode, and in some instances may do so simultaneously. For instance, aremote pilot or driver may wish to leave navigation to an autonomoussystem while manually performing another task, such as operating amechanical system for picking up objects, as an example.

Various types of unmanned vehicles exist for various differentenvironments. For instance, unmanned vehicles exist for operation in theair, on the ground, underwater, and in space. Unmanned vehicles alsoexist for hybrid operations in which multi-environment operation ispossible. Examples of hybrid unmanned vehicles include an amphibiouscraft that is capable of operation on land as well as on water or afloatplane that is capable of landing on water as well as on land.

SUMMARY

An unmanned aerial vehicle (UAV) is disclosed that includes aretractable payload delivery system. The payload delivery system canlower a payload to the ground using a delivery device that secures thepayload during descent and releases the payload upon reaching theground. The location of the delivery device can be determined as it islowered to the ground using image tracking. The UAV can include animaging system that captures image data of the suspended delivery deviceand identifies image coordinates of the delivery device, and the imagecoordinates can then be mapped to a location. The UAV may also beconfigured to account for any deviations from a planned path of descentin real time to effect accurate delivery locations of released payloads.

In one aspect, an example system may include a retractable deliverysystem, an imaging system, and a control system. The retractabledelivery system can include a delivery device, a tether, and aretraction system. The delivery device can be configured to bereleasably coupled to a payload. The tether can be coupled to anunmanned aerial vehicle (UAV) and the delivery device. The retractionsystem can be coupled to the tether and operable to use the tether tolower the delivery device and the payload secured thereby from the UAV.The imaging system can be mounted on the UAV such that, while thedelivery device is suspended from the UAV via the tether, a field ofview of the imaging system includes a light source that is situated onthe delivery device and that is arranged to emit light toward the UAV.The control system can be configured to: (i) while the delivery deviceis suspended from the UAV via the tether, receive image data from theimaging system; (ii) identify, based on the received image data, animage coordinate associated with the light source situated on thedelivery device; and (iii) determine a position of the delivery devicebased at least in part on the identified image coordinate.

In another aspect, an example method may include receiving image datafrom an imaging system while a delivery device is suspended from anunmanned aerial vehicle (UAV) via a tether. The imaging system can bemounted on the UAV such that, while the device is suspended from the UAVvia the tether, a field of view of the imaging system includes a lightsource that is situated on the delivery device and that is arranged toemit light toward the UAV. The example method may also includeidentifying, based on the received image data, an image coordinateassociated with the light source situated on the delivery device. Theexample method may also include determining, based at least in part onthe identified image coordinate, a position of the delivery device.

In another aspect, an example delivery device may include a housing, anelectromechanical component, one or more light sources, a communicationsystem, and a control system. The housing can include a tether anchorconfigured to couple the housing to a tether operable to suspend thehousing via the tether. The electromechanical component can be mountedto the housing. The electromechanical component can be configured to bepositioned in: (i) a first position in which the electromechanicalcomponent engages a payload so as to secure the payload to the housing,and (ii) a second position in which the electromechanical component doesnot engage the payload. The one or more light sources can be mounted tothe housing such that, while the delivery device is suspended from a UAVvia the tether, the one or more light sources are arranged to emit lighttoward the UAV. The communication system can be configured to receiveinformation from the UAV. The control system can be configured to: (i)during a delivery operation in which the delivery device is lowered tothe ground via the tether, cause the electromechanical component to bepositioned in the first position so as to secure the payload to thedelivery device and cause the light source to emit light toward the UAV;(ii) determine that the delivery device is at or near the ground; (iii)receive, via the communication system, an indication from the UAV that adetermined position of the delivery device is within a thresholddistance of a target delivery location, wherein the determined positionof the device is based on image data obtained by an imaging systemsituated on the UAV, wherein the obtained image data comprises an imagewith a field of view including the one or more light sources; and (iv)in response to both determining that the delivery device is at or nearthe ground and receiving the indication from the UAV, move theelectromechanical component from the first position to the secondposition.

In another aspect, a non-transitory computer readable medium has storedtherein instructions executable by a computing device to cause thecomputing device to perform operations. The operations may includereceiving image data from an imaging system while a delivery device issuspended from an unmanned aerial vehicle (UAV) via a tether. Theimaging system can be mounted on the UAV such that, while the device issuspended from the UAV via the tether, a field of view of the imagingsystem includes a light source that is situated on the delivery deviceand that is arranged to emit light toward the UAV. The operations mayinclude identifying, based on the received image data, an imagecoordinate associated with the light source situated on the deliverydevice. The operations may include determining, based at least in parton the identified image coordinate, a position of the delivery device.

In yet another aspect, example systems may include means for receivingimage data from an imaging system while a delivery device is suspendedfrom an unmanned aerial vehicle (UAV) via a tether. Example systems mayalso include means for identifying, based on the received image data, animage coordinate associated with the light source situated on thedelivery device. Example systems may also include means for determining,based at least in part on the identified image coordinate, a position ofthe delivery device.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 1C show a UAV that includes a payload delivery system,according to an example embodiment.

FIG. 1D is a simplified block diagram of an example payload-releasedevice, according to an example embodiment.

FIG. 2A is an aspect view of an example payload-release device.

FIGS. 2B and 2C are side views of the example payload-release devicealigned to engage a payload, and secured to the payload, according toexample embodiments.

FIGS. 2D and 2E are side cross-sectional views of the payload-releasedevice retaining hook in an engaged position and in a disengagedposition, according to example embodiments.

FIG. 2F is a top view of the example payload-release device, accordingto an example embodiment.

FIGS. 3A and 3B are flowcharts of example processes that can beperformed by a payload delivery system during a delivery operation,according to example embodiments.

FIGS. 4A, 4B, and 4C illustrate stages of a delivery operation in whicha location of the descending payload-release device is determined,according to example embodiments.

FIG. 4D illustrates an example system for determining a location of adescending payload-release device, according to an example embodiment.

FIGS. 5A, 5B, and 5C illustrate stages of a delivery operation in whicha location of the descending payload-release device is adjusted,according to example embodiments.

FIG. 5D illustrates an example payload-release device includingthrusters mounted thereon, according to an example embodiment.

FIG. 5E illustrates an example system for adjusting a location of adescending payload-release device, according to an example embodiment.

FIGS. 6A, 6B, 6C, and 6D are simplified illustrations of exampleunmanned aerial vehicles, according to example embodiments.

FIG. 7 is a simplified block diagram illustrating components of a UAV,according to an example embodiment.

FIG. 8 is a simplified block diagram illustrating a distributed UAVsystem, according to an example embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying figures, which form a part hereof. In the figures, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, figures, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the scope of the subject matter presented herein. It willbe readily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

I. Overview

Example embodiments may relate to and/or be implemented in a system inwhich unmanned vehicles, and in particular, “unmanned aerial vehicles”(UAVs), are configured to deliver payloads at delivery locations. UAVsin such a system may operate in an autonomous or semi-autonomousdelivery system in which the UAV carries a payload from a firstlocation, such as a distribution center, to a delivery location, such asa residence or business. At the distribution center, the UAV can beloaded with the payload to be delivered, and then the UAV can navigateto the delivery location. The UAV can then transition to a hover modewhile situated above the delivery location.

While hovering, the UAV can autonomously deliver the payload using aretractable delivery system that lowers the payload to the ground whilethe UAV hovers above. The payload-release device is an apparatus thatfunctions to secure a payload during descent from a hovering UAV, andthen release the payload on the ground, among other functions describedherein. The payload-release device is alternately referred to herein asa delivery device. A winch can unreel and reel in the tether to lowerand raise the payload-release device. The payload-release device can beconfigured to secure the payload while being lowered from the UAV by thetether and release the payload upon reaching ground level. The payloadcan then be retracted to the UAV by reeling in the tether using thewinch. The payload-release device can also include sensors such as abarometric pressure based altimeter and/or accelerometers to assist indetecting the position of the payload-release device (and the payload)relative to the ground. Data from the sensors can be communicated backto the UAV and/or a control system over a wireless link and used to helpin determining when the payload-release device has reached ground level(e.g., by detecting a measurement with the accelerometer that ischaracteristic of ground impact).

The payload-release device can be secured to the payload in a variety ofways. In some examples, the payload includes a payload mount attachmenton its top surface. The payload mount attachment can be a loop extendingfrom the top surface, a hook, or a structure with an aperture. Thepayload-release device can include a channel into which the payloadmount attachment can be inserted. The payload-release device can alsoinclude a retaining rod or hook that can be positioned to engage thepayload mount attachment and release the payload mount attachment. Theretaining rod can be configured to be positioned in: (i) an engagedposition, in which the retaining rod intersects two planes defined byrespective sidewalls of the channel, and (ii) a disengaged position, inwhich the retaining rod does not intersect either plane. For example, inthe engaged position, the retaining rod can cross the channel such thatthe rod engages a rim of the payload mount attachment inserted in thechannel. In the disengaged position, the retaining rod can be withdrawnfrom the channel such that the rod does not interfere with the payloadmount attachment exiting the channel. Thus, in the disengaged position,the retaining rod does not engage the payload mount attachment.

Additionally, or alternatively, the payload-release device may includeclaws and/or gripping members that selectively open and close to graspthe payload and secure the payload by static friction. Thepayload-release device may include hooks or bars configured to engagehandles or apertures in the payload. Further, the payload may beequipped with one or more retaining pins or bumps that engagecorresponding grooves in gripping members that can be actuated to movecloser together (and thereby secure the payload by engaging the pins) ormove apart (and thereby release the payload). In some cases, thepayload-release device may be a vessel with a trap door on bottom thatis closed to secure the payload within, and selectively opened torelease the payload. The payload-release device can use a variety ofother techniques to selectively secure and release payloads.

The payload-release device can include a light source on a top side thatfaces the UAV as the payload-release device is suspended from the UAV.While the payload-release device descends from the UAV, light is emittedupward from the light source to the UAV. An imaging system on the UAVcan then be used to track the location of the descending device bydetecting the upward-directed light and tracking the pixel location ofthe detected light. The imaging system can also compensate for anymotion of the UAV itself and determine the relative translational offsetof the descending device, if any. To reduce the effect of interference,the light source may emit IR and may be operated with a particularamplitude modulation pattern to allow the imaging system to distinguishfrom other sources of IR. In another example, the payload-release devicemay have multiple LEDs that emit light in different colors to therebymake the detected light from the pattern of two or more multi-coloredLEDs more distinguishable from background sources of light in differentenvironments.

The position of the payload-release device (egg) with respect to atarget delivery location can be determined based on any combination of:image tracking from the UAV, inertial sensors on the UAV, GPS, etc.Translational offsets of the descending payload-release device (e.g.,due to wind) with respect to the target delivery location, as determinedin real time, can be compensated for by corresponding translationalmotion of the UAV and/or by operating thrusters on the descending deviceitself. In some examples, upon detecting a drift in the descendingpayload due to wind, the UAV can move parallel to the ground such thatthe payload still lands in the intended delivery location. In someexamples, the payload-release device can generate thrust, independent ofthe UAV, to compensate for wind or other translational forces as thepayload descends from the UAV

To move the payload-release device independent of the UAV, thepayload-release device may have fans or other thrusters mounted to thehousing of the payload-release device. For instance, there may be anarrangement of two reversible fans oriented such that their respectivedirections of thrust (e.g., axes of rotation) are roughly transverse toone another and to the line connected to the UAV. Spinning the two fansin respective directions at respective speeds can thereby produce atranslational thrust perpendicular to the direction of tether tension.In some cases, the payload release device may additionally oralternatively include airfoils (e.g., fins, wings, flaps) that can beactuated to different positions to create a force on the payload viainteraction with the surrounding air.

II. Example System for Delivering a Payload from a Hovering UAV

FIGS. 1A, 1B, and 1C show a UAV 100 that includes a payload deliverysystem 110, according to an example embodiment. As shown, payloaddelivery system 110 for UAV 100 includes a tether 102, atether-deployment mechanism 104, and a payload-release device 106coupled to the tether 102. The payload-release device 106 can functionto alternately secure a payload 108 and release the payload 108 upondelivery. The tether-deployment mechanism 104 can function to unreel andretract the tether 102 such that the payload-release device 106 can belowered to the ground and retracted back to the UAV 100. The payload 108may itself be an item for delivery, and may be housed within (orotherwise incorporate) a parcel, container, or other structure that isconfigured to interface with the payload-release device 106. Inpractice, the payload delivery system 110 of UAV 100 may function toautonomously lower payload 108 to the ground in a controlled manner tofacilitate delivery of the payload 108 on the ground while the UAV 100hovers above.

As shown in FIG. 1A, the payload delivery system 110 may function tohold the payload 108 against or close to the bottom of the UAV 100, oreven inside the UAV 100, during flight from a launch site to a targetlocation 120. The target location 120 may be a point in space directlyabove a desired delivery location. Then, when the UAV 100 reaches thetarget location 120, the UAV's control system may operate thetether-deployment mechanism 104 such that the payload 108, secured bythe payload-release device 106, is suspended by the tether 102 andlowered to the ground, as shown in FIG. 1B. In an example, a controlsystem detects that the payload 108 has been lowered to a point where itis at or near the ground (e.g., at the delivery location). In responseto detecting the payload 108 is at or near the ground, the controlsystem may operate the payload-release device 106 to release the payload108, and thereby detach the payload 108 from the tether 102. Afterreleasing the payload 108, the control system can operate thetether-deployment mechanism 104 to retract the payload-release device106 to the UAV 100, as shown in FIG. 1C. For example, thetether-deployment mechanism 104 may include a winch that reels thetether 102 on and off of a spool to lower and raise the payload-releasedevice 106.

The control system may use various types of data, and varioustechniques, to determine when the payload 108 and/or payload-releasedevice 106 have lowered to be at or near the ground. Further, the datathat is used to determine when the payload 108 is at or near the groundmay be provided by sensors on UAV 100, sensors on the tether 102,sensors on the payload-release device 106, and/or other data sourcesthat provide data to the control system. The control system itself maybe situated on the payload-release device 106 and/or on the UAV 100. Forexample, the payload-release device 106 may include logic module(s)implemented via hardware, software, and/or firmware that cause thepayload-release device 106 to function as described herein, and the UAV100 may include logic module(s) that communicate with thepayload-release device 106 to cause the payload-release device 106 toperform functions described herein.

A. Tether

In practice, the tether 102 used to suspend the payload-release device106 (and payload 108) from the UAV 100 may be formed from a variety ofmaterials. The tether 102 may include, for example, hightensile-strength polymeric fibers, metallic and/or synthetic cables, andother materials that exhibit relatively high tensile-strength per unitweight. The tether 102 may also be selected, at least in part, to be amaterial that is suitable for interfacing with the tether-deploymentmechanism 104. In some examples, the tether 102 may also be operable fortransmitting information between the payload-release device 106 and theUAV 100. For instance, the tether 102 may include, or be coupled to, adata-transmission wire formed of a conductive material (e.g., forconveying data-encoded electrical signals) and/or a fiber optic line(e.g., for conveying data-encoded optical signals).

B. Tether-Deployment Mechanism

In an example the tether-deployment mechanism 104 may include or takethe form of a winch that is configured to deploy the tether with apayload attached thereto (e.g., via the payload-release device 106).Such a winch may include a motor (e.g., a DC motor) that can be activelycontrolled by a servomechanism (also referred to as a “servo”) and amicrocontroller. The microcontroller may output a desired operating rate(e.g., a desired RPM) for the winch, which may correspond to the speedat which the payload 108 should be lowered towards the ground. The servomay then control the winch so that it operates at a desired rate. Inaddition, the winch can be used to retract the tether 102 and thepayload-release device 106 attached thereto following delivery of thepayload 108. Thus, the winch may function to reverse its direction ofrotation to achieve retraction.

In some cases, the tether-deployment mechanism 104 may incorporate or beassociated with an encoder that senses rotation of the spool letting out(or reeling in) the tether 102. Data from such an encoder can then beused by a control system of the UAV 100 to help in determining thedistance between the payload 108 and the ground as the payload 108 isbeing lowered.

In addition, the tether-deployment mechanism 104 may vary the rate atwhich the payload 108 is lowered to the ground or the rate at which thepayload-release device 106 is retracted back to the UAV 100. Forexample, a microcontroller may change the desired rate of loweringand/or retraction according to a variable rate profile and/or inresponse to other factors in order to change the rate at which thepayload 108 descends towards the ground. To do so, the tether-deploymentmechanism 104 may adjust the amount of braking or the amount of frictionthat is applied to the tether. For example, to vary the deployment rate,the tether-deployment mechanism 104 may include friction pads that canapply a variable amount of pressure to the tether. As another example, aline-deployment mechanism 104 can include a motorized braking systemthat varies the rate at which a spool unwinds the tether 102 duringlowering, or reels in the tether 102 during retraction, by makingadjustments to a motor speed (e.g., RPM) or gearing applied to themotor. Other examples are also possible.

In some examples, the tether-deployment mechanism 104 may be attached tothe payload-release device 106, which is lowered with the payload 108,rather than being secured to a housing of the UAV 100. For example, awinch could be attached to the top of the payload-release device 106. Insuch an example, the winch may be operable to hold the payload-releasedevice 106 (and the payload 108) at or near the bottom of the UAV 100during flight to the delivery location. Then, upon arriving at thedelivery location, the winch may function to lower the payload 108 bysliding along the tether 102 and/or using a brake to adjust the rate atwhich the tether 102 is released in accordance with a variable rate.Moreover, in an example that omits the payload-release device 106, sucha top-mounted winch may be mounted directly to the payload 108.

C. Payload-Release Device

FIG. 1D is a simplified block diagram of the payload-release device 106.The payload-release device 106 may take different forms in differentimplementations. The device 106 can be connected to the UAV 100 by thetether 102, and the tether-deployment mechanism 104 on the UAV (e.g., awinch) can reel and unreel the tether 102 to raise and lower the device106 during a delivery operation. The payload-release device 106 can besuspended from the UAV 100 using the tether 102 and can function toalternately secure the payload 108 (e.g., during descent from the UAV)and release the payload 108 (e.g., upon reaching the ground).

As shown in FIG. 1D, the payload-release device 106 may include varioussystems and components, although one or more systems and/or componentsmay be omitted and/or modified in some examples. For example, thepayload-release device 106 may include a processing system 120, a memory122, a communication system 128, a power supply 132, a bystandercommunication module 136, UAV tracking features 140, position sensor(s)150, a translational position system 160, and a payload release system170, each of which may be mounted on or within a housing of the device106 and communicatively coupled to one another. In some examples, thepayload 108 and/or payload-release device 106 may be designed withfeatures that help to prevent the payload 108 and/or the payload-releasedevice 106 from getting stuck or caught during descent (e.g., to preventgetting caught and/or tangled in a tree or on a power line). Forinstance, the payload 108 and/or payload-release device 106 may take theform of or be housed in a teardrop-shaped housing, or another shape thatcan incorporates surfaces that move obstacles aside so as to allow thepayload-release device 106 to be more easily moved up and down by thetether 102 without getting stuck.

i. Processing System

The processing system 120 may be configured to provide various functionsdescribed herein. The processing system 120 may include or take the formof program instructions stored in a non-transitory computer-readablemedium (e.g., the memory 122) and may also include a variety offunctional modules implemented by software, firmware, and/or hardware.

The processing system 120 may include one or more general purpose orspecial purposes microprocessors in communication with memory 122.Memory 122 may include a non-transitory computer-readable medium. Inpractice, the processing system 120 may cause the payload-release device106 to perform certain functions by executing program instructions 124stored in memory 122. For instance, upon execution of the programinstructions 122, the processing system 120 may obtain sensor data fromthe position sensors 150, and generate command signals that cause anactuator 172 of the payload release system 170 to move so as to engageor disengage the payload 108 based on characteristics of the obtainedsensor data. In some cases, the processing system 120 may additionallyor alternatively include hardware-implemented and/orfirmware-implemented logic modules. The memory 122 can also include data126, which may be used to store information particular to the specificpayload-release device 106. For instance, the data 126 may includeinformation related to a model number and/or serial number of the device106 and/or information related to calibration of the position sensors150 (or other systems), or operation of other systems in thepayload-release device 106 (e.g., communication protocols used by thecommunication system 128).

ii. Communication System

The communication system 128 can be used to send and receive databetween the payload-release device 106 and the UAV 100. For example, thecommunication system 128 may be a wireless communication system thatsends and receives data-encoded electromagnetic transmissions using anantenna to create a wireless data link 130 with the UAV 100.

The communication system 128 can function to send and receiveinformation to and from the UAV 100. In some examples, the communicationsystem 128 can include an antenna structure and can operate to exchangeinformation with the UAV via a wireless communication link 130. Thecommunication system 128 may additionally or alternatively send andreceive information over a wireline link, such as a data transmissionlink incorporated with the tether 102. The communication system 128 mayalso include a modem for modulating and demodulating signals transmittedto and from the UAV 100. Among other features, the communication system128 can allow for a control system associated with the UAV 100 to accessinformation generated by sensors in the payload-release device 106 andvice versa. Additionally, the communication system 128 can allow fordeterminations related to operation of the payload-release device to bemade by the processing system 120 in the payload-release device 106and/or by a control system associated with the UAV 100 (e.g., a controlsystem on the UAV 100 and/or a control system in communication with theUAV 100).

iii. Power Supply

The payload-release device 106 can include various systems and/orcomponents that consume electrical power, such as the sensors 150, thecommunication system 128, the processing system 120, etc. The powersupply 132 can provide power to such systems in the payload-releasedevice 106. The power supply 132 may include a battery 134 and/or acapacitive device that can be charged with electrical energy, forexample. The battery 134 may be charged through charging terminals 135accessible from the exterior of the payload-release device 106. In someexamples, the charging terminals 135 may include conductive pads thatare arranged to electrically couple to corresponding terminals on theUAV 100 while the payload-release device 106 is secured to the UAV 100(e.g., during flight mode operations of the UAV). For example, thecharging terminals 135 may electrically couple to correspondingterminals on the UAV 100 when the payload-release device 106 is seatedagainst the UAV 100. The battery 134 within the payload-release device106 can then be recharged via the electrical connection.

Moreover, in some examples, such an electrical connection between thepayload-release device 106 and the UAV 100 may be facilitated by thepayload-release device 106 including an asymmetric surface that isreceived within a corresponding mating surface of the UAV 100 (e.g., arelief of the asymmetric surface). As the payload-release device 106 isbeing retracted toward the UAV 100, the asymmetric surface can interfacewith the mating surface to cause the payload-release assembly to rotateto a particular orientation at which the asymmetric surface is alignedwith the mating surface. By ensuring the payload-release device 106becomes seated against the UAV 100 in a repeatable orientation, theelectrical contacts/terminals between the device 106 and the UAV 100 canbe aligned for electrical connection. The asymmetric surface and/ormating surface may also include guide pins and corresponding receivingchannels to facilitate self-alignment of the electrical contacts as thepayload-release device 106 approaches the UAV 100. Additionally oralternatively, the electrical contacts/terminals may be arranged to beat least partially rotation insensitive. For example, a surface of thepayload-release device 106 that is seated against the UAV 100 may becylindrically symmetric (e.g., a conical surface) and be received into acorresponding mating surface on the UAV. The contacts/terminals mayinclude cylindrically symmetric conductive rings at respective radii ofthe two cylindrically symmetric mating surfaces. As a result, theelectrical contact between the respective terminals may be achievedregardless of the rotational orientation of the payload-release device106. Other examples of self-aligned and/or rotation insensitiveelectrical and/or communication terminals between the payload-releasedevice 106 and the UAV 100 are also possible.

In another example, the payload-release device 106 may be chargedwirelessly. In particular, both the UAV 100 and the payload-releasedevice 106 can include antennas for sending and harvesting energy,respectively. The UAV's power supply antenna may be situated along theexterior surface of the UAV or within the UAV, near the mating locationwhere the payload-release device 106 is seated during flight mode.Similarly, the payload-release device 106 can have an energy-harvestingantenna situated near the surface of the payload-release device that isseated against the UAV 100 during flight mode. To charge thepayload-release device, the power supply antenna can transmit energy ata particular power. The radiated energy induces voltage variationsacross the energy harvesting antenna in the payload-release device, andthose voltage variations can be regulated and/or rectified byelectronics therein to supply a charging current to the battery or otherpower supply module within the payload-release device. Among otherbenefits, a wireless charging connection may allow for relativelygreater alignment tolerances between the payload-release device 106 andthe mating surface of the UAV 100 that the payload-release device 106 iswithdrawn to during flight mode. A wireless charging connection may alsodecrease the number of exposed electrical terminals required on thepayload-release device, which may enhance durability andweather-resistance. Further, the power supply antenna and theenergy-harvesting antenna may be configured to enhance the efficiency ofpower transfer from the power supply antenna and the energy-harvestingantenna, such as by an impedance matching technique, for example.

In some cases, the payload-release device 106 may additionally oralternatively be powered via electrical signals conveyed over the tether102 (or another conductive linkage between the UAV 100 and thepayload-release device 106).

iv. Bystander Communication System

The bystander communication system 136, which can be used to generateaudible and/or visible cues for perception by people near a deliverylocation while the device 106 is raised and lowered. The various cuesgenerated by the bystander communication module 136 are selected tofacilitate safe, intuitive interactions between bystanders on the groundand a UAV delivery system.

The bystander communication system 136 can include one or more humaninterface modules configured to generate cues perceptible to people onthe ground. For example, the bystander communication system 136 mayinclude a light source and/or an audio source. The light source mayinclude a lighting system that flashes or changes colors to indicatedifferent states of the delivery system (e.g., one cue as thepayload-release device 106 descends from the UAV 100, and a second cueas the payload-release device 106 is retracted back to the UAV 100). Thelight source may include one or more individual light emissive elements,such as light emissive diodes, and/or light transmissive elements, suchas a liquid crystal device. For instance, the light source may include adisplay panel of emissive or transmissive elements on which scrollingtext messages or pictures can be rendered. The audio source may includea loudspeaker that functions to output sound waves for perception bypeople on the ground. For instance, the loudspeaker may emit one audiocue during payload descent to provide a cue to bystanders and/or payloadrecipients that the payload is approaching the ground (e.g., a recordingor synthesized voice saying “Please stand back as your package is beingdelivered” or another warning message), and another audio cue followingpayload delivery to provide a cue that the delivery is complete (e.g., arecording or synthesized voice saying “You can now collect your package”or another message).

In addition to interface and/or communication capabilities performed bythe bystander communication system 136, the UAV delivery system mayinclude back-end processes to facilitate communications with particularindividuals who are payload recipients. For instance, the system maygenerate and send messages to payload recipients via variouscommunication networks (e.g., cellular telecommunication networks, widearea networks, such as the Internet, etc.). In a particular example, acontrol system associated with the UAV delivery system may send a givenintended payload recipient one or more communications via text messages,emails, etc., so as to inform the recipient of the progress of thedelivery process. Such messages may include indications of: an estimateddelivery time, an anticipated time until payload delivery, indicationsthat the payload (or UAV bearing the payload) has departed for thedelivery location, has reached a predetermined distance from thedelivery location, has arrived at the delivery location, that thepayload is descending toward the ground, and/or that delivery is nowcomplete. In some cases, moreover, the system may allow for an intendedrecipient to send responsive communications to the UAV control system soas to effect a modification of one or more delivery parameters,including, without limitation, a delivery time, a delivery location,and/or other aspects of the delivery process. Additionally, the systemmay allow the intended recipient to accept, deny, and/or re-direct agiven payload via communication with the control system. Other examplesare also possible.

v. UAV Tracking Features

The payload-release device 106 can include features 140 that facilitateposition tracking using the UAV 100. For example, the payload-releasedevice 106 may include one or more reflector(s) 142 and/or emitter(s)144 situated on the payload-release device 106 so as to direct lighttoward the UAV 100 while the payload-release device 106 is suspendedfrom the UAV 100 via the tether 102. For instance, the reflectors(s) 142may include an arrangement of reflective surfaces mounted on a topsurface of a housing of the payload-release device 106. Similarly, theemitter(s) 144 may include one or more sources of radiation, such aslight emissive diodes mounted to a top surface of the housing of thepayload-release device 106. The reflective surfaces 142 and/or emitters144 can then be detected using an imaging system on the UAV 100 that isarranged to capture a field of view including the payload-release device106 while the payload-release device 106 is suspended from the UAV 100via the tether 102. The imaging system on the UAV 100 can capture animage of the suspended payload-release device 106. The image can then beused to identify a current location of the payload-release device 106with respect to the field of view of the imaging system. In particular,the captured image can be analyzed to identify a location in the imagethat corresponds to the arrangement of reflectors 142 and/or emitters144. The identified location can then be mapped to a correspondinglocation of the suspended payload-release device 106.

For instance, the imaging system on the UAV 100 may include a camerasituated on a gimbal mount so as to have a substantially fixeddownward-facing perspective of the region below the UAV 100. During adelivery operation, such a camera can then be used to track thepayload-release device 106 by identifying a region of a captured imagethat includes the reflector(s) 142 and/or emitter(s) 144. The identifiedregion or image coordinate in the captured image can then be mapped to alocation of the payload-release device 106 based on the current locationand orientation of the UAV 100, the orientation of the imaging systemwith respect to the UAV 100, and the altitude difference between the UAV100 and the payload-release device 106.

The reflectors 142 and/or emitters 144 may be configured to assist inidentifying the reflectors 142 and/or emitters 144 and in distinguishingthem from background light sources. In some examples, the reflectors 142and/or emitters 144 may be arranged in a pattern in which one or more ofthe reflectors 142 and/or emitters 144 are physically separated from oneanother. In some examples, the reflectors 142 and/or emitters 144 mayreflect/emit light with different colors. In some examples, thereflectors 142 and/or emitters 144 may emit light at a particularwavelength and the imaging system may filter incoming light for thatwavelength. For example, the emitter 144 may be an infrared LED or thereflector 142 may be configured to preferentially reflect infrared light(e.g., from infrared radiation emitted by the UAV 100). Other examplesare also possible in which the reflectors 142 and/or emitters 144 arearranged so as to provide a pattern of light that can be identified fromimage data captured by an imaging system on the UAV 100.

In examples in which the tracking features 140 include two or morereflectors 142 and/or light sources 144, the relative orientation of thefeatures 140 can be used to determine an orientation of thepayload-release device 106 (e.g., a degree of rotation about an axisdefined by the tether 102). For example, if the payload-release device106 includes two LEDs, one on each side, and the two emit light indifferent colors (or are otherwise distinguishable via modulation,intensity, etc.), the location of the two emitters with respect to oneanother can be used to determine a degree of rotation of thepayload-release device 106 about the tether 102.

Furthermore, the observed separation between multiple emitters 144(and/or reflectors 142) can be used to estimate the altitude distancebetween the imaging system on the UAV 100 and the payload-releasedevice. That is, for a given perspective ratio of the imaging system,emitters separated by a fixed amount appear closer together, as measuredin image coordinates (e.g., pixels), when the emitters are distant fromthe imaging system, than when the emitters are closer to the imagingsystem. The system may therefore use separations measured in imagecoordinates to estimate a distance to the payload-release device 106,and thus an altitude of the payload-release device 106. Similarly, ifthe tracking system is informed of the altitude of the payload-releasedevice 106 from another source (e.g., an altimeter on thepayload-release device 106), the imaging system may tune a patternrecognition routine and/or identification routine to scale a pattern ofemitters being searched for within obtained image data.

In some examples, the upward-facing emitter 144 may emit light in anarrow wavelength range (e.g., a light emissive diode that emits at anarrow band of frequencies) and the imaging system on the UAV 100 mayinclude a corresponding narrow band filter that passes the emittedlight. The filter on the imaging system can thus preferentially selectthe light from the emitter 144 while decreasing interference from otherlight. The payload-release device 106 can thereby be identified withinan image captured by the imaging system more readily than otherwisepossible. In order to determine a position of the payload-release device106 from the image data, an image coordinate at which the trackingfeatures 140 are identified is mapped to a physical location based on ageometric relationship between the orientation of the imaging systemfield of view and the altitudes of the UAV 100 and the payload-releasedevice 106. In some examples, the imaging system may be mounted on astabilizing mount, such as a three-dimensional gimbal mount, so as tosubstantially fix an orientation of the imaging system with respect tothe orientation of the UAV 100 and/or the ground. As such, a given imagecoordinate of a captured image obtained using the stabilized imagingsystem can be mapped to a line in the field of view of the imagingsystem that extends between the imaging system and the ground. Combiningthe direction information with information regarding the currentaltitude of the payload-release device 106 can then allow fordetermining the three-dimensional location of the payload-releasedevice.

Moreover, because the imaging system is situated on the UAV 100, at aperspective so as to look down on the payload-release device 106 as itis suspended from the UAV 100 via the tether 102, the locationinformation derived via the image tracking system may be useful inidentifying the location of the payload-release device in a surfacetransverse to the direction of the tether 102. To the extent that theimaging system is arranged with a perspective that is close to aconnection point between the tether 102 and the UAV 100 (e.g., near thetether-deployment mechanism 104), image coordinates of the imagingsystem can be mapped to locations of the payload-release device 106 onsurfaces defined by fixed lengths of the tether 102. That is, for agiven length of deployed tether, the payload-release device 106 can beconstrained to move along a surface on which each point is the samedistance from the tether attachment point on the UAV 100, and thatdistance is defined by the length of deployed tether. The differentlocations along that surface can each be mapped to a particular imagecoordinate in the field of view of the imaging system. Thus, thethree-dimensional location of the payload-release device 106 withrespect to the UAV 100 can be determined based on the length of deployedtether (or another indicator of the altitude of the payload-releasedevice) and image coordinates at which the tracking features 140 areobserved via the imaging system on the UAV 100. The accuracy of thedetermined location is then a function of the imaging resolution and theresolution of the altitude indicator.

vi. Position Sensors

The sensor(s) 150 can include one or more systems that generate dataindicative of the altitude, position, and/or status of thepayload-release device 106 and/or the payload 108. The sensor(s) 150 mayinclude inertial motion sensor (IMU) 152 (e.g., accelerometers and/orgyroscopes) that function to generate data indicative of rotationaland/or translational motion of the payload-release device 106. Thesensor(s) 150 may additionally or alternatively include an altitudesensor 154, such as a barometric altimeter that functions to measure thelocal atmospheric pressure, which can be used to estimate the currentaltitude of the payload-release device 106. The sensor(s) 150 mayadditionally or alternatively include an active ranging system 156 suchas a laser ranging system or radio ranging system that estimates thedistance to the ground based on time of flight of reflected radiationtransmitted by the payload-release device 106 and reflected from theground. Similarly, such active ranging systems may function to estimatethe distance to the UAV 100 from which the payload-release device 106 issuspended.

The sensor(s) 150 may additionally or alternatively include imagingsystem(s) that function to capture image data or video from a cameramounted on the payload-release device 106. The imaging system(s) mayinclude, for example a pair of cameras that can be used to estimate thedistance to the ground stereoscopically, for instance, by focusing thetwo spatially separated cameras on a common ground feature anddetermining distance based on the angle between the cameras. Othersensors may include proximity sensors and/or encoders that function toprovide an indication of whether the payload 108 is secured to thepayload-release device 106. The sensor(s) 150 can function to generatesensor data indicative of the various parameters they are configured tomeasure, and the sensor data can then be provided to the UAV 100 (viathe communication system 128) and/or to the processing system 120 on theUAV 100.

Moreover, in some examples, sensor data related to the position of thepayload-release device 106 may be generated by, or in cooperation with,components on the UAV 100. For example, a position tracking system mayinclude an upward-facing light source and/or reflector mounted on thepayload-release device 106 (e.g., the tracking features 140), and adownward-facing imaging system mounted on the UAV 100. The imagingsystem can track the position of the suspended payload-release assembly106 by tracking the location of the upward-facing light source and/orreflector in the field of view of the imaging system. The UAV 100 mayalso include other sensors that generate data related to the position ofthe payload-release device, such as an encoder that indicates a lengththe tether 102 deployed from the tether-deployment mechanism 104, andthus an altitude of the payload-release device, a line tension sensorthat indicates a degree of tension on the tether 102 and thus whetherthe payload-release device 106 is resting on the ground, a thrust sensorthat indicates an amount of thrust provided by the UAV's propulsionsystem and thus whether the payload-release device 106 is resting on theground, and/or other sensors.

For example, the length of the tether 102 that has been let out by thetether-deployment mechanism 104 may be used to determine the distancebetween the payload 108 and the ground (i.e., the altitude of thepayload 108). More specifically, given the height of the payload 108,the height of the payload-release device 106, the length of the tether102, and the altitude difference between the top of the tether 102 andthe point where altitude is measured by the UAV 100, the UAV 100 maydetermine the distance between the bottom of the payload 108 and theground. Thus, the distance between the payload 108 and the ground can beupdated as the line 102 is deployed, which may be indicated by readingsfrom an encoder associated with the tether-deployment mechanism 104.

Data from the sensors 150 can then be used to estimate the altitudeand/or position of the payload-release device 106 as it is lowered tothe ground. For example, the accelerometer data and/or altimeter datacan be used to determine how far the payload-release device 106 (and thepayload 108) has been lowered using the tether 102, and thus how muchdistance remains to the ground. In addition, data from the accelerometer152 may be used to detect a collision with the ground by thepayload-release device 106 and/or the payload 108. Such a collisionevent may be indicated by the accelerometer data as an abruptdeceleration event with a characteristic signature, for example. In someexamples, impact with the ground may be indicated by acceleration (asindicated by data from an accelerometer mounted in the payload-releasedevice 106) with a magnitude that exceeds a threshold. Information fromsuch sensors can then be communicated to the UAV 100 using thecommunication system 128. Moreover, the determination that the device106 is at or near the ground may be based on one or more factors,including sensor data from position sensors on the device 106 (e.g.,accelerometer and/or altimeter data), sensor data from sensors on theUAV 100 (e.g., encoder, image data, and/or tether tension data), and/ora communication from a remote control system (e.g., a remote operatormay observe a video feed or other indicia and alert the UAV 100 when thedevice 106 is at or near the ground).

vii. Translational Positioning System

The payload-release device 106 can include a translational positioningsystem 160. The translational positioning system 160 can includethrusters 162 and/or air foils 164 that can be used to apply force onthe payload-release device 106 while the payload-release device 106 issuspended from the UAV 100 via the tether 102. The translationalpositioning system 160 uses one or more components to interact with thesurrounding air to generate force on the payload-release device 106 andmay be alternately referred to herein as an air propulsion system. Thethruster 162 and/or air foil 164 can apply force on the payload-releasedevice 106 in a direction that is at least partially transverse to thedirection of the tether 102 as the payload-release device 106 issuspended from the UAV 100 via the tether 102. For instance, thethruster 162 can include a turbine, fan, or other rotating blade mountedto the housing of the payload-release device 106. The thruster 162 mayalso be situated within a shroud to both direct airflow and to protectthe blade and other objects from interfering with moving parts of thethruster 162 (e.g., rotating blades). The airfoil 164 may include a wingor sail of rigid or flexible material that is mounted to the housing ofthe payload-release device 106 so as to apply force on thepayload-release device 106 via interaction with air surrounding thepayload-release device 106.

For example, a pair of thrusters may be oriented to generate thrusttransverse to one another and transverse to the tether 102. Operatingthe thrusters 162 in respective directions can therefore cause thepayload-release device 106 to move in a desired direction transverse tothe direction of the tether 102. Moreover, the payload-release device106 can be moved along the direction of the tether 102 by reeling thetether 102 in and out (e.g., via the tether-deployment mechanism 104).Thus, the payload-release device 106 can be moved along a desiredthree-dimensional path by manipulating both the tether-deploymentmechanism 104 and the translational positioning system 160.

In practice, the translational positioning system 160 may be used toadjust the location of the payload-release device 106 as it descends viathe tether 102 according to position feedback information from theimaging system used to track the tracking features 140, from theposition sensors 150, and/or from other sources. For example, thetranslational positioning system 160 may be used to cause thepayload-release device 106 to descend along a particular path of descentassociated with an intended delivery location. The path of descent maybe, for example, a predicted path along which the payload-release device106 will travel to the intended delivery location. The path of descentmay be, for example, a straight line normal to the ground (e.g., inconditions with no wind or other atmospheric disturbances that applyforce to the payload-release device other than gravity). The path ofdescent may also be, for example, a path that account for wind applyingforce on the suspended payload-release device 106 in a direction atleast partially transverse to the direction of the tether 102. A controlsystem (e.g., on the UAV 100) can be used to monitor the positioninginformation to detect a deviation from the predetermined path ofdescent. The control system can then cause the translational positioningsystem 160 to direct the descending payload-release device 106 towardthe predetermined path of descent. Additionally or alternatively, thecontrol system may adjust a position of the hovering UAV 100 to at leastpartially compensate for a detected deviation from the predeterminedpath of descent.

viii. Payload Release System

The payload-release device 106 can also include a payload-release system170, which can include one or more electromechanical components that canbe manipulated to alternately secure the payload 108 or release thepayload 108. The payload-release system 170 can include one or moreactuator(s) 172 (e.g., a solenoid, motor, hydraulic component, etc.),grippers 176 (e.g., clamps, opposable arms, etc.), retaining rods orhooks 174, or other components. The actuator 172 may be mechanicallylinked to the retaining rod 174 and/or gripping surface 176 tofacilitate moving the rod 174 and/or gripper 176 between differentpositions in response to electronically generated signals (e.g., fromthe processing system 120). For example, in one position, component(s)of the payload release system 170 can couple the payload-release device106 to the payload 108, and in another position, component(s) of thepayload release system 170 can release the payload 108 from thepayload-release device 106.

The payload-release system 170 may secure the payload 108 to thepayload-release device 106 in different ways. In some examples,grippers, fasteners, or other engaging surfaces function to secure thepayload 108 (e.g., by applying pressure to the payload 108 or byengaging corresponding surfaces of the payload 108). In some cases, thepayload 108 may include one or more apertures or other standardizedinterfacing features configured to interface with the payload-releasedevice 106. Thus, the payload-release device 106 may include prongs orthe like that interface with the payload 108 by passing through thepayload's apertures (or otherwise engaging standardized features). Thepayload-release device 106 can also release the payload 108 bydisengaging the grippers or engaging surfaces, or by detaching from thepayload's standardized features.

In some cases, the retaining rod 174 may include a hook that is rotatedbetween different positions via the actuator 172. In one position, therod 174 can engage an aperture of a payload mount attachment while themount attachment is inserted within a channel formed in a housing of thepayload-release device 106. The mount attachment may be a substrate orother structure that extends from a top surface of the payload 108 andhas an aperture formed therein for receiving the rod 174. While thelowering the payload 108 from the UAV 100, the mount attachment can beinserted into the channel and the rod 174 can cross through the aperture(e.g., by crossing through the channel) so as to engage the payload 108.The rod 174 can then be withdrawn from the channel to release thepayload 108 from the payload-release device 106 once the payload 108 ison the ground.

Additionally or alternatively, the payload-release device 106 mayinclude opposable arms. The opposable arms can be used to grip thepayload 108 while lowering the payload 108 from the UAV 100, and thencan be separated to release the payload 108 once the payload 108 is onthe ground. Additionally or alternatively, the payload-release device106 may also take the form of a container, bucket, cage, or otherenclosure with a bottom (or other enclosing surface) that can be openedand/or removed. While the payload 108 is lowered from the UAV 100, thepayload 108 can be secured within the enclosure, and then the bottom ofthe enclosure can be opened once payload 108 is on the ground.Additionally or alternatively, the payload-release device 106 mayinclude one or more magnetic features, which may or may not beactivated/deactivated in response to an input, such as permanentmagnets, paramagnetic materials, electromagnets, etc. In such anexample, the payload 108 may also include magnetic features, which mayor may not be activated/deactivated in response to an input, and thepayload 108 can be secured to the payload-release device 106 viamagnetic attractive forces between such magnetic features and then thepayload 108 can be released by deactivating at least one of the magneticfeatures or by overcoming the attractive force. Additionally oralternatively, the payload-release device 106 may include an engagingrod or hook that engages a corresponding depression or aperture in thepayload 108. For example, the payload 108 may be formed to include oneor more loops along its top or side surfaces. To secure the payload, therod(s) or hook(s) of the payload-release device 106 can be maneuvered toengage such loops. Similarly, the payload can be released bymanipulating the rod(s) or hook(s) to disengage the loops. In someexamples, the rod, hook, or other payload-engaging mechanism may beimplemented as: a coupling link with a portion that opens and closes,similar to a carabiner; a hook mounted below the payload-release device106 (i.e., not mounted to pass within a channel); and/or a closed loopthat engages a hook on the payload 108 and then translates and/orrotates to disengage from the hook during payload release. Thepayload-release device 106 may additionally or alternatively includeother examples of devices, mechanisms, features, and systems may also beused to alternately engage a payload via a mechanical connection and, inresponse to determining it is time to release the payload, release thepayload via manipulation of one or more components on thepayload-release device 106 and/or payload 108.

Various other types of payload-release systems are also possible. Theform of a payload-release device for a particular implementation maydepend on, for example, the types of payloads to be delivered and theenvironmental conditions in which delivery will be made. For example,the payload-release device 106 may be positioned on the tether 102 or atthe top of the tether 102, and may be operable to cut the tether orrelease the tether from the UAV 100 when the payload 108 is at or nearthe ground.

D. Control System

The UAV 100 may include or be associated with a control systemconfigured to provide various functions described herein. The controlsystem may include or take the form of program instructions stored in anon-transitory computer-readable medium and may also include a varietyof functional modules implemented by software, firmware, and/orhardware. In some examples, the control systems described herein mayinclude components located in the payload-release device 106, in the UAV100, and/or at a remote location and in communication with the UAV 100.However, the various components are configured to communicateinformation amongst one another to coordinate functioning of the UAV 100and the payload-release device 106 such that determinations can be madeand/or actions can be performed by one component on the basis ofinformation obtained via other components communicatively linked to thatcomponent.

The control system may be configured to autonomously navigate the UAV100 toward a specified destination. For example, the control system maydetermine a set of flight-command instructions that cause propulsionsystems of the UAV 100 to operate such that the UAV flies through a setof waypoints that define a route to the specified destination. Amongother factors, the control system may plan routes based on informationfrom other aerial vehicles (or control systems therefore) and/or basedon pre-determined guidance, regulations, and/or other constraintsregarding allowable routes, altitudes and speeds in particular regions,etc. The control system may also be configured to operate the payloaddelivery system 110 to controllably lower the payload 108 to the ground,release the payload 108, and then retract the payload-release device 106back to the UAV 100. Thus, the control system can function to regulatethe operation of a variety of actuators, servo controls, and otherelectromechanical devices that are involved in the operation of thepayload delivery system 110.

The control system of UAV 100 may also control the payload-releasedevice 106 to release the payload 108 at or near the ground. Forexample, the control system may trigger the payload-release device 106to release the payload 108 (e.g., by actuating the payload releasesystem 170) after a certain length of the tether 102 has been let out bythe tether-deployment mechanism 104, such that it is expected that thepayload 108 is on the ground, or near enough to the ground that it cansafely drop to the ground. The control system may also receive sensordata from an accelerometer on the payload-release device 106, anddetermine that the payload 108 is on the ground when the accelerometerdata indicates that the payload 108 had an impact with the groundfollowed by remaining at rest. Other examples are also possible in whichthe control system can function to determine that the payload 108 is ator near the ground and then responsively cause the payload-releasedevice 106 to release the payload 108.

In some cases, the control system can operate the payload deliverysystem 110 such that the rate of descent of the payload 108 is altitudedependent. For example, the control system can initially allow thepayload 108 to descend at a maximum rate of descent. The control systemcan monitor information from sensors indicating the descending altitudeof the payload 108, and upon detecting that the payload 108 is within aparticular distance of the ground, the control system can cause thetether-deployment mechanism 104 to begin slowing the descent of thepayload 108. The control system may cause the rate of descent to slow toa predetermined safe speed by the time the payload 108 is near enough tothe ground that it could interfere with (or be grabbed by) objects orpeople on the ground. Similarly, the control system may also cause thepayload-release device 106 to ascend back to the UAV 100 in analtitude-dependent manner after releasing the payload 108.

E. Example Payloads

The payload 108 may be a standardized container or parcel that includesone or more features configured to interface with the payload-releasedevice 106. For instance, the payload 108 may include one or more loops,indentations, tabs, anchor points, or other structural features arrangedto be engaged by corresponding components of the payload-release device106 (e.g., the payload release system 170). In some cases, thestandardized features of the payload 108 may be integrated in apackaging module (e.g., a reusable or disposable container), and thepackaging module may house (or be fastened to) one or more items thatare being delivered using the UAV 100. Such items may include food,medical equipment or supplies, retail goods, relief items, or any otheritems that may be delivered by a delivery service. In some cases, thedelivered items may be supplied to stranded or isolated people in anemergency or rescue scenario. In some cases, the payload 108 may alsoinclude an identifying element to facilitate recognition and/ordifferentiation, of the payload 108 from other payloads when beingsorted and handled. The identifying element may include an RFID tag oran optically scanned linear or two-dimensional barcode. The identifyingelement can then be associated with information regarding the particularpayload in a database that can be accessed by various systems used inhandling/sorting payloads, and in loading the UAV 100. For example, sucha database may associate the identifying element with contents of thepayload, delivery destination, and/or other information pertaining tothe particular payload and its delivery. Systems interfacing with agiven payload can then scan its identifying element and retrieve theinformation from the database that relates to the given payload.

In some examples, the payload 108 may take the form of a container thatincludes medical-support devices and/or other items intended to help ina medical situation. In other examples, the payload 108 may itself be amedical-support device (e.g., a defibrillator) or another type ofmedical support item, such as a pharmaceutical medicine. Generally, thepayload 108 may include any type of item to be delivered, includingnon-medical items such as goods ordered from a non-medical deliveryservice or items shipped through a shipping service.

F. Emergency-Release System

In yet a further aspect, a UAV 100 may include an emergency-releasesystem (not shown in the Figures), which is configured to cut or releasethe tether 102 from the UAV 100. In particular, the UAV 100 may beconfigured to detect certain emergency situations, such as the tether102, payload-release device 106, and/or payload 108 becoming stuck(e.g., in a tree or other obstacle), and to automatically cut the tether102 when such an emergency situation is detected. The emergencysituation may also involve the tether 102 and/or payload-release device106 being grabbed by an individual on the ground. By cutting the tether102 in such emergency situations, the UAV 100 can prevent damage to orfrom the UAV 100, such as may occur in a scenario where the UAV 100 ispulled to the ground by an entangled tether 102.

Various types of emergency-release mechanisms are possible. Theemergency-release mechanisms may be configured to cut the tether 102 orotherwise release the tether 102 from the UAV 100. In one example, theemergency-release mechanism may include a blade mounted on a cartridgethat can be propelled through a firing cylinder by igniting a chemicalexplosive or propellant. The firing cylinder can be mounted on the UAV100 near the tether-retraction mechanism 104 such that, when fired, themotion of the cartridge causes the blade to sever the tether 102 andthereby disconnects the unreeled tether 102 (and payload-release device106) from the UAV 100.

Further, various types of data may be analyzed to determine if and whenan emergency-release mechanism should be used to release the tether 102.The control system can function to determine that such an emergencysituation has occurred based on data from sensors on the UAV 100 and/orthe payload-release device 106. Indications of the emergency situationmay be provided by the position sensors 150 in the payload-releasedevice 106 and/or from sensors generating data indicative of a conditionof the tether 102 (e.g., a line tension sensor). Further, the UAV'scontrol system could analyze image data from a camera, data from aline-tension sensor, data from sensors monitoring thrust exerted by theUAV's propulsion systems, and/or other types of data to determine thatthe payload 108 and/or payload-release device 106 is stuck, has beeninterfered with, or that deployment of the payload 108 has otherwisefailed. Upon determining that an emergency situation has occurred, thecontrol system can responsively use the emergency-release mechanism torelease the payload 108 and/or the payload-release device 106 (e.g., bysevering the tether 102). In some cases, the control system may receivean indication of the emergency situation from a remote terminal where asupervisory control operator is monitoring sensor data and hasdetermined that the tether 102 should be cut (e.g., based on analyzing avideo feed from imaging system(s) associated with the UAV 100).

G. Other Aspects

In some examples, the UAV 100 may include features that can hold thepayload 108 in place and/or stabilize the payload during flight. Suchfeatures may be mechanically adjustable such that the tether-deploymentmechanism 104 can lower the payload 108 upon arriving at the deliverylocation. For instance, in the configuration shown in FIG. 1A, UAV 100includes moveable retaining brackets 114. The brackets 114 may interfacewith the payload 108 and/or device 106 to hold the payload 108 in placeduring flight, as shown in FIG. 1A. And when UAV 100 reaches thedelivery location, the brackets 114 may be moved away from payload 108,so that the payload 108 can be lowered without interference from thebrackets 114. Note that other types of mechanisms may also be used tohold the payload 108 in place and/or to stabilize the payload 108 duringflight. Moreover, the payload 108 may be held in place during flight bythe device 106, without use of any additional features.

Further, in some implementations, the payload delivery system 110 mayomit the payload-release device 106. For example, the payload itself mayincorporate a rolling mechanism that traverses the tether 102 and simplyrolls off the end of the tether 102 upon reaching the end, therebyreleasing the payload 108 from the UAV 100.

In some examples, a UAV 100 may additionally or alternatively beconfigured to pick up items from the ground using the payload deliverysystem 110 shown in FIGS. 1A-1D, or a different type of system.

III. Example Payload-Release Device

FIG. 2A is an aspect view of an example payload-release device 200. Thepayload-release device 200 may include some or all of the functionalityof the payload-release device 106 described in connection with FIGS.1A-1D. The payload-release device 200 includes a housing 210, which maytake a variety of forms. In some examples, the housing 210 may be anenclosure formed of a rigid material such as metal and/or plastic. Thehousing 210 may have surfaces designed to help prevent the device frombecoming stuck or entangled while being lowered or raised by the tether.For example, the housing 210 may have a generally cubic or cuboid shapewith rounded or partially rounded corners and/or edges betweensidewalls. Many other shapes are possible.

The housing 210 can include a bottom surface 212 that includes a channel220. The bottom surface 212 may be a surface configured to be facedagainst a payload while the payload-release device 200 is secured to thepayload. Thus, the bottom surface 212 may be generally flat (i.e.,planar) or may be another surface that is configured to mate against asurface of a payload. The channel 220 may be integrally formed in thebottom surface 212, or may be a cutout region of the bottom surface 212.The channel 220 includes sidewalls 222, 224, which have a separationthat defines a width of the channel 220. The sidewalls 222, 224 may beapproximately transverse to the bottom surface 212 and the sidewalls222, 224 may optionally be connected to one another by respective endwalls that define a length of the channel 220 transverse to its width.The sidewalls 222, 224 may also have a non-constant separation distancethroughout the depth of the channel 220. For example, near the bottomsurface 212, the sidewalls 222, 224 may be separated by a greaterdistance than further within the channel 220. Moreover, the sidewalls222, 224 may be angled so as to become gradually closer to one another,at greater depths within the channel 220. As such, a payload mountattachment inserted into the channel 220 (e.g., the attachment 240 inFIG. 2B) can be at least partially aligned and/or guided into thechannel by the sidewalls 222, 224.

A retaining hook 230 is shown in an engaged position in FIG. 2A. Theretaining hook 230 crosses the channel 220. The retaining hook 230 canpass through respective entry locations in the sidewalls 222, 224 tocross the width of the channel 220. As described below, while in theengaged position, a payload mount attachment inserted into the channel220 can be secured by the retaining hook 230. The retaining hook 230 canalso be withdrawn from the channel 220, which allows a payload mountattachment to exit the channel 220 without interference. Thus, theretaining hook 230 can be positioned to alternately: (i) engage apayload mount attachment inserted in the channel 220 and thereby securethe payload to the payload-release device 200, and (ii) release apayload mount attachment from the channel 220 and thereby release thepayload from the payload-release device 200.

FIG. 2B is a side view of the example payload-release device 200 alignedto engage a payload 248. FIG. 2C is a side view of the examplepayload-release device 200 secured to the payload 248. The payload 248includes a top surface 246. The top surface 246 of the payload 248 maybe a generally flat surface, or another surface that is configured tointerface with the bottom surface 212 of the payload-release devicehousing 210. A payload mount attachment 240 is situated on the topsurface 246. The payload mount attachment 240 is configured to bereceived within the channel 220 and be engaged by the retaining hook230. The payload mount attachment 240 can include a structure 242 thatextends approximately transverse to the top surface 246. An aperture 244in the structure 242 can then receive the retaining hook 230 while thestructure 242 is inserted into the channel 220, which is shown in FIG.2C. In particular, the retaining hook 230 can make contact with a rim ofthe aperture 244, which contact can mechanically couple thepayload-release device 200 to the payload mount attachment 240 (and thusthe payload 248). The structure 242 may be, for example a substrate suchas a polymeric and/or fiber-based substrate. In some instances, thestructure 242 may be a cardboard structure that extends from a cardboardpackaging enclosure for the payload 248.

FIGS. 2D and 2E are side cross-sectional views of the payload-releasedevice 200 retaining hook 230 in an engaged position and in a disengagedposition. The depth of the channel 220 extends to an end wall 226, whichcan connect the sidewalls 222, 224. The retaining hook 230 can includean engagement surface 236 that extends between an elbow 234 and an end232. The retaining hook 230 can enter the channel through entrylocations 223, 225, which can be formed in the sidewalls 222, 224 toallow insertion of the retaining hook 230 into the channel 220. Theentry locations 223, 225 can also be seen in FIG. 2A. In the engagedposition, which is shown in FIG. 2D, the engagement surface 236 of theretaining hook 230 crosses between the two sidewalls 222, 224 of thechannel 220. As a result, if a structure is inserted into the channel220, the structure is enclosed by the engagement surface 236, the endwall 226, and the sidewalls 222, 224. In the disengaged position, whichis shown in FIG. 2E, the retaining hook 230 is withdrawn from thechannel 220 entirely. In particular, the engagement surface 236 does notcross the sidewalls 222, 224, and as a result a structure inserted inthe channel 220 is not prevented from exiting the channel 220. While thedisengaged position shown in FIG. 2D illustrates the retaining hook 230entirely withdrawn from the channel 220 (i.e., the end 232 is outsidethe entry location 225), some examples may involve a portion of theretaining hook 230 situated within the channel 230 during disengagement(e.g., the end 232 passing through the entry location 225, but not entrylocation 223).

The retaining hook 230 is mounted within the housing 210 on an axle 238so as to rotate about an axis defined by the axle 238. The axle can beoriented transverse to the width of the channel 220 such that rotatingthe retaining hook 230 causes the engagement surface 236 to move intoand out of the channel 220. The axle 238 can be positioned within thehousing 210 at a depth greater than the depth of the channel 220, andapproximately centered with respect to planes defined by the twosidewalls 222, 224. Other configurations are possible. For instance, theaxle may be located at a different location and/or orientation withinthe housing 210, and the retaining hook may take a different form so asto effect insertion and withdrawal of the retaining hook 230 in responseto rotary actuation of the retaining hook with respect to the axle.Moreover, the retaining hook 230 may be implemented by a rod (or anotherstructure) that is actuated by a linear actuator, rotary actuator,stepper motor, hydraulic system, etc. so as to alternately insert andwithdraw the rod to and from the channel.

The retaining hook 230 and/or the payload mount attachment 240 can beformed of a rigid or semi-rigid material such as metal, plastic,composite, and/or paper-based substrates. The retaining hook 230 can bedesigned to have sufficient tensile strength to secure the payload 248via the payload mount attachment 240 while the payload undergoesaccelerations expected during a delivery and/or flight operations, forexample.

FIG. 2F is a top view of the example payload-release device 200. The topsurface 214 of the housing can include a tether anchor 260. The tetheranchor 260 can be an attachment point for coupling a tether to thepayload-release device 200. The tether anchor 260 may include, forexample, a pair of apertures 262, 264 and the tether can be coupledthereto by inserting the tether into one of the apertures 262, 264 andbringing it out of the other. Once threaded through the tether anchor260, the tether may be coupled to itself using a clamp, knot, of anothertechnique. The tether anchor 260 may be reinforced by an internal and/orexternal structure of the housing 210 in some examples to allow thetether anchor 260 to transmit forces from the tether exerted on thepayload-release device and/or payload. Moreover, in some casespayload-release devices may include alternate tether anchorimplementations and/or alternative physical features configured tocouple the housing to a tether that is suspended from a UAV. Forinstance, some examples may include a tether anchor configured as a hookthat receives a loop in a tether suspended from a UAV, one or moreclamps that squeeze a suspended tether, a winch device that can be usedto wind/unwind a portion of a suspended tether coiled around an axle ofthe winch device. Many other examples of tether anchors are alsopossible.

The top surface 214 can also include a first light emitting diode (LED)250 and a second LED 252. The LEDs 250, 252 can be used to track theposition of the payload-release device 200 while it is suspended fromthe UAV, for example using an imaging system on the UAV. In some cases,the LEDs 250, 252 can emit light in different colors (e.g., one red, onegreen) to facilitate distinguishing the pair of LEDs 250, 252 frombackground light sources. In some cases, the LEDs 252, 254 may bedistinguishable from one another by one or more other factors, such asintensity, modulation pattern, etc. The LEDs 252, 254 may also bearranged on the top surface 214 in a manner that is rotation-variant(e.g., in a rotation-variant pattern). As a result, the positions of thetwo LEDs 252, 254, as observed via an imaging system on a hovering UAV,can be used to determine an orientation of the payload-release device200.

IV. Example Operations

FIGS. 3A and 3B are flow charts illustrating processes that may beperformed by a payload delivery system in connection with a deliveryoperation. FIG. 3A is a flowchart of an example process 300 that can beperformed by a payload delivery system during a delivery operation. Inparticular, the process 300 involves determining a location of apayload-release device using an imaging system on a UAV to trackfeatures of the payload-release device. The process 300 may be performedusing either of the payload delivery systems described in connectionwith FIGS. 1A-2F.

At block 302, a payload-release device is suspended from a hovering UAV.For example, the UAV may be hovering over a delivery location, and thepayload-release device may be suspended from the hovering UAV by atether. The payload-release device may then be lowered to the groundwhile securing a payload by a tether-deployment mechanism on the UAV.

At block 304, light sources on the payload-release device are caused toemit light toward the UAV. The light sources may be mounted on a topsurface of the payload-release device such that the emitted light isdirected toward the UAV. For example, the LEDs 252, 254 mounted on thetop surface 214 of the payload-release device 200 may be used to emitlight toward the UAV from which the device 200 is suspended.

At block 306, an imaging system on the UAV is used to obtain image dataof the suspended payload release device. The imaging system may bemounted on the UAV so as to capture a field of view that includes thesuspended payload-release device while the payload-release device issuspended from the UAV. The imaging system may include, for example, acamera mounted on a gimbal mount so as to substantially maintain aperspective and/or field of view of the imaging system with respect tothe UAV. The imaging system may also be configured to detect light fromthe light sources on the payload-release device and distinguish thatlight from background light. For example, the imaging system may filterincoming light to selectively detect light at wavelength correspondingto the light sources on the payload-release device. For example, thelight sources may emit light at an infrared or near infrared wavelength.Generally, the light sources may emit light at a range of differentwavelengths of light (i.e., electromagnetic radiation). The imagingsystem may also be configured to detect modulation patterns of incominglight. As such, the light sources on the payload-release device may beemitted with a particular intensity modulation pattern to facilitateidentification of the light sources by the imaging system and to betterdistinguish the light from the light sources from background lightsources.

At block 308, image coordinates of the light source can be identifiedwithin the obtained image data. For example, the image data obtained bythe imaging system can be analyzed to identify a pattern in the imagedata that corresponds to the light sources. The image analysis caninclude identifying a pattern within the obtained image, a particularwavelength, a particular modulation pattern, or another identifiablefeature corresponding to the light sources mounted on thepayload-release device. In some cases, the image analysis can alsoinvolve analyzing a subset of an obtained image frame that correspondsto an expected area of the payload-release device. The expected area maybe estimated based on sensor data from other sources, such as an IMU,GPS, or other system on the payload-release device. In addition, theanalysis may involve adjusting an expected intensity and/or scale of thepattern to be identified based on sensor data indicating a distance tothe payload-release device from the imaging system. The distance to thepayload-release device may be estimated from data from an IMU,altimeter, GPS, ranging system, etc. on the payload-release device,and/or based on an encoder that tracks the length of tether deployedfrom the UAV. Upon identifying a pattern of light within the obtainedimage data that corresponds to the light source, image coordinates ofthe pattern may be specified as pixel coordinates or another unit.

At block 310, a location of the payload-release device can be determinedbased on the identified image coordinates. For example, a particularimage coordinate can be mapped to a line that projects from the imagingsystem primary aperture, within the field of view of the imaging system.Data indicating the altitude of the payload-release device and/or dataindicating the distance from the imaging system primary aperture to thepayload-release device can then be used to determine a point on thatline at which the payload-release device is located. Altitude data maycome from an altimeter or inertial motion unit or anotherposition-related sensor on the payload-release device, for example.Distance data may come from a sensor that tracks the length of deployedtether, for example. Thus, a given pixel coordinate can be mapped to athree dimensional location, relative to the location of the UAV.

The image data could be used to estimate the distance between thepayload-release device and the UAV (e.g., the altitude of thepayload-release device). For instance, the image data may be analyzed toidentify a pattern that corresponds to the spatial arrangement of thelight sources on the top of the payload-release device. For example, foran arrangement of two or three (or more) lights sources, the actualspacing between each of the lights in the arrangement is known. Theimage can be analyzed to determine the separations between imagecoordinates corresponding to each light source (e.g., pixel distances)within the field of view of the imaging system. The distance between thepoints of each light source in image coordinates (e.g., pixel distances)can then be combined with the known physical separations to estimate thedistance to the payload-release device. Thus, combining the knownspacing information with the scale of the field of view of the cameramay be used to estimate the distance to the payload-release device basedon the apparent separation between the lights within the field of viewof the camera. For instance, the closer together the lights appear inthe field of the image, the further the payload-release device is fromthe camera, and vice versa. The current distance (or at least a roughdistance range) to the payload-release device may be based on computinga ratio between the apparent separation between lights in the camera'sfield of view to a reference image coordinate separation thatcorresponds to reference distance.

Moreover, the image data may be used to determine an orientation of thepayload-release device during descent. For example, while thepayload-release device is suspended by the tether, the payload-releasedevice may rotate (i.e., twist) around the axis defined by the tether.The pattern of light detected by the imaging system can be used todetermine the rotation of the payload-release device. For example, ifthe payload-release device includes two light sources that aredistinguishable from one another (e.g., by intensity modulation,wavelength, etc.), the positions of the two light sources in the imagedata can be mapped to an orientation of the payload-release device.Further, the payload-release device may include more than two lightsources arranged in a rotation-asymmetric pattern. As such, thepositions of the light sources may be determined based on the image dataand the orientation of the payload-release device can be determinedbased on the pattern in which the light sources are arranged.

FIG. 3B is a flowchart of an example process 320 that can be performedby a payload delivery system during a delivery operation. In particular,the process 320 involves determining a location of a payload-releasedevice and then correcting for deviations from a planned path of descentof the payload. The process 320 may be performed using either of thepayload delivery systems described in connection with FIGS. 1A-2F.

At block 322, a payload delivery system is used to lower a payload froma hovering UAV. For example, the UAV may be hovering at a targetlocation above a delivery location on the ground. The UAV can then useits retractable delivery system to lower the payload-release device, andthe payload secured thereby, such as by unreeling the tether from awinch on the UAV. The payload-release device can include a retaining rodthat can be alternately positioned in an engaged position, in which theretaining rod engages the payload, and a disengaged position, in whichthe retaining rod does not interfere with the payload as it is released.The retaining rod may engage the payload through a payload mountattachment of the payload (e.g., a structure with an aperture thatenters a channel in the payload-release device). As such, in thedisengaged position, the retaining rod does not engage the payload mountattachment.

At block 324, payload-release device is secured to the payload as thepayload-release device (and the payload secured thereby) descends fromthe UAV. The payload-release device may therefore include anelectromechanical component that can be alternately positioned in anengaged position, in which the component engages the payload so as tomechanically couple to the payload, and a disengaged position, in whichthe component does not prevent the payload from being released from thepayload-release device. The payload-release device securing the payloadmay involve positioning a retaining rod so as to engage an aperture in apayload mount attachment, for example.

At block 326, the location of the suspended payload-release device isdetermined. Determining the location may involve the process 300described in connection with FIG. 3A, for example. Additionally oralternatively, the location determination of block 326 may involve usingsensor data from various sensors on the payload-release device and/orthe UAV to determine the current location of the payload-release device.For instance, accelerometer data may be used to incrementally determinea path of the payload-release device as it descends from the UAV.

At block 328, a determination is made whether the payload-release devicehas deviated from a predetermined path of descent associated with thedelivery location. The predetermined path of descent may be a straightpath that is roughly normal to the ground and extends from the deliverylocation. Such a straight vertical path of descent may be predicted inthe absence of wind or other effects that cause the payload-releasedevice to experience forces transverse to the direction of tension inthe tether. At block 328, a control system may evaluate whether thedetermined location of the payload-release device is within a thresholddistance of the predetermined path of descent. The threshold distancemay, in some cases, vary depending on the predicted effect on theeventual landing. For instance, a small distance from a predicted pathof descent early in the descent (i.e., at a high altitude) may bedetermined to exceed the threshold deviation if the deviation isexpected to result in a large offset in landing location. On the otherhand, a small distance from the predicted path of descent when thepayload is already near the ground may not exceed the thresholddeviation.

In some cases, the predicted path of descent may vary from a straightvertical path of descent and may be based on sensors and/orcommunications indicating weather conditions, such as measurements ofwind speed, etc. The predicted path of descent may then be a path ofdescent that is predicted to end at the desired delivery location giventhe atmospheric conditions. The predicted path of descent may alsoaccount for expected variations in wind speed at different altitudes.The predicted path of descent may also account for atmospheric effectsdue to structures in the vicinity of the delivery location, such ashouses, trees, or other structures that may block the wind. In somecases, for example, the predicted path of descent may initially varyfrom a straight vertical path, at high altitudes, and then swing backtoward a substantially straight vertical path, at altitudes below a windblock created by surrounding structures. The predicted path of descentfor a given delivery location may therefore be based on real time dataof the atmospheric conditions (e.g., wind speed sensors), data of thedelivery location (e.g., image data used to recognize structures),and/or archival data (e.g., three dimensional maps of deliverylocations, data from previous deliveries at similar or relatedlocations, etc.).

If, at block 328, the location of the payload-release device is found tohave deviated from the predetermined path of descent, the process 320can continue at block 330. If, at block 328, the location of thepayload-release device is not found to have deviated from thepredetermined path of descent, the process 320 can continue at block326, and the location of the payload-release device can be determinedagain before checking whether the determined location has deviated fromthe predetermined path of descent.

At block 330, the deviation from the predetermined path of descent canbe accounted for by causing the payload-release device and/or the UAV tomove so as to compensate for the deviation. Causing the payload-releasedevice to move is discussed in connection with block 332, and causingthe UAV to move is discussed in connection with block 334. Generally, acontrol system can be configured to determine a degree of movement to beperformed by the payload-release device and/or the UAV based on avariety of factors, including the degree of deviation from thepredetermined path of descent, atmospheric conditions, weight of thepayload, constraints due to obstacles, etc.

At block 332, the payload-release device can be moved using atranslational positioning system mounted to a housing of thepayload-release device to generate force on the payload-release devicevia interaction with the surrounding atmosphere (e.g., an air propulsionsystem). For example, the translational positioning system may includethrusters, such as an arrangement of blades within a shroud that canrotate to generate thrust on the payload-release device that istransverse to the tension from the tether. In some cases, two thrustersmay be reversible and may be arranged so as to generate thrust roughlytransverse to one another and transverse to the direction of tensionfrom the tether. Operating two such thrusters at respective speeds inrespective directions allows for a range of different forces transverseto the direction of the tether to be applied to the payload-releasedevice. The translational positioning system may additionally oralternatively include an air foil such as a wing or sail that can bepositioned in different orientations so as to interact with thesurrounding atmosphere to generate force on the payload-release device.

At block 334, the UAV can be moved by generating flight control commandsfor the UAV propulsion system that cause the UAV to move. In oneexample, the flight control commands may be generated to cause the UAVto traverse an offset that corresponds to an expected distance from aprojected landing location of the payload and a target deliverylocation. In practice, the control system may estimate, based on thedegree of deviation from the predetermined path of descent and otherfactors a revised path of descent for the delivery location, and thenthe UAV can be moved to a location for the revised path of descent.Other examples are also possible, including an incremental approach inwhich the position of the UAV is repeatedly adjusted to compensate fordeviations from an initial predetermined path of descent as the payloadis lowered to the ground.

At block 336, the payload is determined to be at or near the ground andalso at or near the delivery location. The determination may be made bya computing control system on the payload-release assembly and/or theUAV (or associated with the UAV). The determination may involvedetermining the location of the payload-release device (e.g., similar toblock 326) and then determining whether the location is within athreshold distance of the delivery location. The determination may bebased, at least in part, on sensor data from sensors on thepayload-release device. For example, data from inertial motion sensor(s)included in the payload-release device can be analyzed to determinewhether such data indicates that the payload and/or payload-releaseassembly underwent an impact with the ground. Upon detecting anacceleration sequence characteristic of a ground impact, the computingsystem(s) can determine that the payload is at or near the ground.Additionally or alternatively, the determination may be made in partbased on altimeter sensor data, imaging data, tether reel encoder data,tether-tension sensor data, and/or UAV thrust sensor data. Thetether-tension sensor data and/or UAV thrust sensor data can be used,for example, to determine the amount of weight suspended from the UAV bythe tether. A sudden decrease in the amount of suspended weight may thusindicate that the payload is on the ground. Other techniques fordetermining that the payload is at or near the ground and at or near thedelivery location are described above in connection with FIGS. 1A-1D.

At block 338, the payload can be released from the payload-releasedevice. Releasing the payload may involve actuating an electromechanicalcomponent so as to move the component from a position in which thepayload is engaged to a position in which the payload is notmechanically linked to the payload-release device. For instance,releasing the payload may involve moving a retaining rod from theengaged position to the disengaged position to thereby release thepayload from the payload-release device.

At block 340, the payload-release device is retracted back to the UAV.For example, a tether-deployment mechanism, such as a winch or ratchet,can be operated to reel in the tether. The released payload remains onthe ground, at the delivery location, as the payload-release device isretracted back to the UAV.

In practice, one or more of the operations described in connection withthe processes 300 and 320 may be omitted or performed in a differentorder. Various combinations and/or variations of the processes 300 and320 are therefore possible, and are included within the presentlydisclosed subject matter.

V. Example Operation Sequences

FIGS. 4A, 4B, and 4C illustrate stages of a delivery operation in whicha location of the descending payload-release device is determined. FIG.4A shows a UAV 400 hovering over the ground. A payload 408 is secured toa payload-release device 406 that is suspended from the UAV 400 by atether 402. The tether 402 couples the payload-release device 406 to atether-deployment mechanism 404. The payload-release device 406 includestracking features 420 which emit and/or reflect light 422 toward the UAV400 while the payload-release device is suspended via the tether 420.The UAV 400 includes an imaging system 430 that is arranged to obtainimage data of a field of view that includes the suspendedpayload-release device 406. The imaging system 430 may be mounted to theUAV 400 with a gimbal mount or another stabilizing mount so as tomaintain a perspective and/or field of view with respect to the UAV 400.As shown in FIG. 4A, the imaging system 430 may be arranged such thatthe payload-release device 406 is roughly at an image center 410 ofobtained images when the payload-release device 406 is suspendedstraight vertically (e.g., in the absence of wind).

FIG. 4B shows the payload-release device 406 experiencing a forcetransverse to the direction of tension in the tether 402 (e.g., due towind). As a result, the payload-release device 406 and the payload 408are offset from the image center 410 when imaged by the imaging system430. The tracking features 420 can still emit and/or reflect light 422toward the imaging system 430 to allow the image data from the imagingsystem 430 to be used to track in the location of the suspendedpayload-release device 406.

FIG. 4C represents the determination of the location of thepayload-release device from the image data. The image data is used toidentify an image coordinate at which the image includes a patterncorresponding to the tracking features 420. The image coordinatecorresponding to the tracking features 420 is then mapped to a line 432that projects outward from the primary aperture of the imaging system430, with an angle based on the image coordinates. As shown in FIG. 4C,the projected line 432 is at an angle □ from the image center 410, andintersects the payload-release device 406. The identified imagecoordinates thus indicate that the payload-release device 406 (or thetracking features 420) is located along the projected line 432. Inaddition, data indicating an altitude of the payload-release device 406and/or a length of the deployed tether 402 can be used to determine thelocation along the projected line 432 at which the payload-releasedevice 406 is located.

FIG. 4D illustrates an example system 440 for determining a location ofa descending payload-release device. The system 440 includes a controlsystem 454 which receives image data 450 and altimeter data 452 and usesthat data as a basis to determine location data 456. The control system454 may be implemented by computing systems located on thepayload-release device 406 and/or the UAV 400 that is configured toperform the process 300 described in connection with FIG. 3A. The imagedata 450 can be generated by the imaging system 430, and the altimeterdata 452 can be generated by a sensor on the payload-release device 406,for example. Other examples are possible.

A graphical representation of the image data 450 is illustrated in frame441. The frame 441 can correspond to the field of view of the imagingsystem 430. The frame 441 depicts an image center 442 (represented bythe “X”), and image representations of the payload 448 and the trackingfeatures on the payload-release device (e.g., light sources 444, 446).The control system 454 can analyze the image data 450 to identify theimage coordinates at which the tracking features are depicted. Thelocation can then be determined based on an intersection between aprojected line corresponding to those image coordinates and an altitudeof the payload-release device 406, which can be indicated by thealtimeter data 452.

FIGS. 5A, 5B, and 5C illustrate stages of a delivery operation in whicha location of the descending payload-release device is adjusted. FIG. 5Ashows a UAV 500 hovering over a delivery location. A payload 508 issecured to a payload-release device 506 that is suspended from the UAV500 by a tether 502. The tether 502 couples the payload-release device506 to a tether-deployment mechanism 504. The payload-release device 506includes tracking features 520 which emit and/or reflect light 522toward the UAV 500 while the payload-release device is suspended via thetether 520. The UAV 500 includes an imaging system 530 that is arrangedto obtain image data of a field of view that includes the suspendedpayload-release device 506. The imaging system 530 may be mounted to theUAV 500 with a gimbal mount or another stabilizing mount so as tomaintain a perspective and/or field of view with respect to the UAV 500.The imaging system 530 may be arranged such that an image center 410 ofobtained images is approximately vertically downward from the UAV 500.The payload-release device 506 can also include a translationalpositioning system 524, which may include thrusters and/or air foils forgenerating force on the payload-release device 506 via interaction withthe surrounding atmosphere.

As shown in FIG. 5A, a predicted path of descent 532 of thepayload-release device may be approximately straight vertically downwardto the delivery location. However, during descent, wind can apply forceto the payload-release device 506 (and the payload 508) in a directiontransverse to the tether 502, which causes the payload-release device tomove in the direction of the applied force, swinging on the tether 502.Thus, the payload-release device 506 has deviated from the predeterminedpath of descent 532 associated with the delivery location.

FIG. 5B shows the payload-release device 506 (and the payload 508) beingmoved back to the predicted path of descent 532. The translationalpositioning system 524 is used to generate a thrust that counters thewind. As a result, the payload-release device 506 (and payload 508) canmove back to the predetermined path of descent 532 and continuedescending toward the delivery location.

FIG. 5C shows the payload-release device 506 (and the payload 508) beinglowered along a revised path of descent 534. To account for the wind,the UAV moves in a direction opposite the force of wind. The effect ofthe wind can be used to determine the revised path of descent 534 forthe delivery location, and the UAV 500 can move to a location along therevised path of descent 534. From the new location of the UAV 500, thepayload-release device 506 can descend to the delivery location.

FIG. 5D illustrates the example translational positioning system 524,which may also be referred to herein as an air propulsion system. Thepositioning control system 524 can include thrusters 540 a, 540 bmounted to the housing the of the payload-release device 506. As shownin FIG. 5D, the thrusters 540 a, 540 b may be mounted on a top surface536 of the housing, nearest the tether 502, although other locations arepossible. The thruster 540 a can include a propeller 542 situated withina shroud 544 (e.g., a fan). The propeller can include two or more bladesthat rotate about an axis at least partially transverse to the directionof the tether 502. The blades of the propeller 542 can be angled withrespect to one another so as to generate thrust in a direction along theaxis of rotation. Moreover, the propeller 542 may be reversible suchthat the thruster 540 a can be used to generate thrust in opposingdirections depending on the direction of rotation of the propeller 542.The thruster 540 b can be similar to the thruster 540 a, but orientedapproximately transverse to the thruster 540 b. By operating the twothrusters at respective speeds and in respective directions acombination of forces can be applied to the payload-release device 506in directions transverse to the direction of tension in the tether 502.

FIG. 5E illustrates an example system 55 for adjusting a location of adescending payload-release device. The system 550 includes a controlsystem 554 which receives payload location data 552 and uses that dataas a basis to determine payload thrust controls 556 and/or UAV flightcontrols 558. The control system 554 may be implemented by computingsystems located on the payload-release device 506 and/or the UAV 500that is configured to perform the process 320 described in connectionwith FIG. 3B. The payload location data 552 can be generated by animage-based position tracking system similar to the system 450 describedin connection with FIGS. 4A-4D. Additionally or alternatively, thepayload location data 552 may be based on position sensors on thepayload-release device, such as accelerometer data that is used toincrementally determine a path traversed by the payload-release deviceduring descent from the UAV. The payload thrust controls 556 may involveelectronic signals that cause one or both thrusters 540 a, 540 b togenerate force on the payload-release device in a particular directionthat compensates for an offset from the predetermined path of descent,for example. The UAV flight controls 558 may involve electronic signalsthat cause a propulsion system of the UAV 500 to operate so as to causethe UAV 500 to traverse a desired path that compensates for an offsetfrom the predetermined path of descent, for example.

VI. Example UAVs

FIGS. 6A, 6B, 6C, and 6D are simplified illustrations of exampleunmanned aerial vehicles, according to example embodiments. Herein, theterms “unmanned aerial vehicle” and “UAV” refer to any autonomous orsemi-autonomous vehicle that is capable of performing some functionswithout a physically-present human pilot. Examples of flight-relatedfunctions may include, but are not limited to, sensing its environmentor operating in the air without a need for input from an operator, amongothers.

A UAV may be autonomous or semi-autonomous. For instance, some functionscould be controlled by a remote human operator, while other functionsare carried out autonomously. Further, a UAV may be configured to allowa remote operator to take over functions that can otherwise becontrolled autonomously by the UAV. Yet further, a given type offunction may be controlled remotely at one level of abstraction andperformed autonomously at another level of abstraction. For example, aremote operator could control high level navigation decisions for a UAV,such as by specifying that the UAV should travel from one location toanother (e.g., from the city hall in Palo Alto to the city hall in SanFrancisco), while the UAV's navigation system autonomously controls morefine-grained navigation decisions, such as the specific route to takebetween the two locations, specific flight controls to achieve the routeand avoid obstacles while navigating the route, and so on. Otherexamples are also possible.

A UAV can be of various forms. For example, a UAV may take the form of arotorcraft such as a helicopter or multicopter, a fixed-wing aircraft, ajet aircraft, a ducted fan aircraft, a lighter-than-air dirigible suchas a blimp or steerable balloon, a tail-sitter aircraft, a glideraircraft, and/or an ornithopter, among other possibilities. Further, theterms “drone”, “unmanned aerial vehicle system” (“UAVS”), or “unmannedaerial system” (“UAS”) may also be used to refer to a UAV.

FIG. 6A is a simplified illustration of a UAV 600, according to anexample embodiment. In particular, FIG. 6A shows an example of arotorcraft 600 that is commonly referred to as a multicopter.Multicopter 600 may also be referred to as a quadcopter, as it includesfour rotors 602. It should be understood that example embodiments mayinvolve rotorcraft with more or less rotors than multicopter 600. Forexample, a helicopter typically has two rotors. Other examples withthree or more rotors are possible as well. Herein, the term“multicopter” refers to any rotorcraft having more than two rotors, andthe term “helicopter” refers to rotorcraft having two rotors.

Referring to multicopter 600 in greater detail, the four rotors 602provide propulsion and maneuverability for the multicopter 600. Morespecifically, each rotor 602 includes blades that are attached to amotor 604. Configured as such the rotors may allow the multicopter 600to take off and land vertically, to maneuver in any direction, and/or tohover. Furthermore, the pitch of the blades may be adjusted as a groupand/or differentially, and may allow a multicopter 602 to performthree-dimensional aerial maneuvers such as an upside-down hover, acontinuous tail-down “tic-toc,” loops, loops with pirouettes,stall-turns with pirouette, knife-edge, immelmann, slapper, andtraveling flips, among others. When the pitch of all blades is adjustedto perform such aerial maneuvering, this may be referred to as adjustingthe “collective pitch” of the multicopter 600. Blade-pitch adjustmentmay be particularly useful for rotorcraft with substantial inertia inthe rotors and/or drive train, but is not limited to such rotorcraft

Additionally or alternatively, multicopter 600 may propel and maneuveritself adjust the rotation rate of the motors, collectively ordifferentially. This technique may be particularly useful for smallelectric rotorcraft with low inertia in the motors and/or rotor system,but is not limited to such rotorcraft.

Multicopter 600 also includes a central enclosure 606 with a hinged lid608. The central enclosure may house, for example, control electronicssuch as an inertial measurement unit (IMU) and/or an electronic speedcontroller, batteries, other sensors, and/or a payload, among otherpossibilities.

The illustrative multicopter 600 also includes landing gear 610 toassist with controlled take-offs and landings. In other embodiments,multicopters and other types of UAVs without landing gear are alsopossible.

In a further aspect, multicopter 600 includes rotor protectors 612. Suchrotor protectors 612 can serve multiple purposes, such as protecting therotors 602 from damage if the multicopter 600 strays too close to anobject, protecting the multicopter 600 structure from damage, andprotecting nearby objects from being damaged by the rotors 602. Itshould be understood that in other embodiments, multicopters and othertypes of UAVs without rotor protectors are also possible. Further, rotorprotectors of different shapes, sizes, and function are possible,without departing from the scope of the invention.

A multicopter 600 may control the direction and/or speed of its movementby controlling its pitch, roll, yaw, and/or altitude. To do so,multicopter 600 may increase or decrease the speeds at which the rotors602 spin. For example, by maintaining a constant speed of three rotors602 and decreasing the speed of a fourth rotor, the multicopter 600 canroll right, roll left, pitch forward, or pitch backward, depending uponwhich motor has its speed decreased. Specifically, the multicopter mayroll in the direction of the motor with the decreased speed. As anotherexample, increasing or decreasing the speed of all rotors 602simultaneously can result in the multicopter 600 increasing ordecreasing its altitude, respectively. As yet another example,increasing or decreasing the speed of rotors 602 that are turning in thesame direction can result in the multicopter 600 performing a yaw-leftor yaw-right movement. These are but a few examples of the differenttypes of movement that can be accomplished by independently orcollectively adjusting the RPM and/or the direction that rotors 602 arespinning.

FIG. 6B is a simplified illustration of a UAV 620, according to anexample embodiment. In particular, FIG. 6B shows an example of atail-sitter UAV 620. In the illustrated example, the tail-sitter UAV 620has fixed wings 622 to provide lift and allow the UAV to glidehorizontally (e.g., along the x-axis, in a position that isapproximately perpendicular to the position shown in FIG. 6B). However,the fixed wings 622 also allow the tail-sitter UAV 620 take off and landvertically on its own.

For example, at a launch site, tail-sitter UAV 620 may be positionedvertically (as shown) with fins 624 and/or wings 622 resting on theground and stabilizing the UAV 620 in the vertical position. Thetail-sitter UAV 620 may then take off by operating propellers 626 togenerate the upward thrust (e.g., a thrust that is generally along they-axis). Once at a suitable altitude, the tail-sitter UAV 620 may useits flaps 628 to reorient itself in a horizontal position, such that thefuselage 630 is closer to being aligned with the x-axis than the y-axis(e.g., aligned parallel to the ground). Positioned horizontally, thepropellers 626 may provide forward thrust so that the tail-sitter UAV620 can fly in a similar manner as a typical airplane.

Variations on the illustrated tail-sitter UAV 620 are possible. Forinstance, tail-sitters UAVs with more or less propellers, or thatutilize a ducted fan or multiple ducted fans, are also possible.Further, different wing configurations with more wings (e.g., an“x-wing” configuration with four wings), with less wings, or even withno wings, are also possible. More generally, it should be understoodthat other types of tail-sitter UAVs and variations on the illustratedtail-sitter UAV 620 are also possible.

As noted above, some embodiments may involve other types of UAVs, inaddition or in the alternative to multicopters. For instance, FIGS. 6Cand 6D are simplified illustrations of other types of UAVs, according toexample embodiments.

In particular, FIG. 6C shows an example of a fixed-wing aircraft 640,which may also be referred to as an airplane, an aeroplane, or simply aplane. A fixed-wing aircraft 640, as the name implies, has stationarywings 642 that generate lift based on the wing shape and the vehicle'sforward airspeed. This wing configuration is different from arotorcraft's configuration, which produces lift through rotating rotorsabout a fixed mast, and an ornithopter's configuration, which produceslift by flapping wings.

FIG. 6C depicts some common structures used in a fixed-wing aircraft640. In particular, fixed-wing aircraft 640 includes a fuselage 644, twohorizontal wings 642 with an airfoil-shaped cross section to produce anaerodynamic force, a vertical stabilizer 646 (or fin) to stabilize theplane's yaw (turn left or right), a horizontal stabilizer 648 (alsoreferred to as an elevator or tailplane) to stabilize pitch (tilt up ordown), landing gear 650, and a propulsion unit 652, which can include amotor, shaft, and propeller.

FIG. 6D shows an example of an aircraft 660 with a propeller in a pusherconfiguration. The term “pusher” refers to the fact that the propulsionunit 668 is mounted at the back of the aircraft and “pushes” the vehicleforward, in contrast to the propulsion unit being mounted at the frontof the aircraft. Similar to the description provided for FIG. 6C, FIG.6D depicts common structures used in the pusher plane: a fuselage 662,two horizontal wings 664, vertical stabilizers 666, and a propulsionunit 668, which can include a motor, shaft, and propeller.

UAVs can be launched in various ways, using various types of launchsystems (which may also be referred to as deployment systems). A verysimple way to launch a UAV is a hand launch. To perform a hand launch, auser holds a portion of the aircraft, preferably away from the spinningrotors, and throws the aircraft into the air while contemporaneouslythrottling the propulsion unit to generate lift.

Rather than using a hand launch procedure in which the person launchingthe vehicle is exposed to risk from the quickly spinning propellers, astationary or mobile launch station can be utilized. For instance, alaunch system can include supports, angled and inclined rails, and abackstop. The aircraft begins the launch system stationary on the angledand inclined rails and launches by sufficiently increasing the speed ofthe propeller to generate forward airspeed along the incline of thelaunch system. By the end of the angled and inclined rails, the aircraftcan have sufficient airspeed to generate lift. As another example, alaunch system may include a rail gun or cannon, either of which maylaunch a UAV by thrusting the UAV into flight. A launch system of thistype may launch a UAV quickly and/or may launch a UAV far towards theUAV's destination. Other types of launch systems may also be utilized.

In some cases, there may be no separate launch system for a UAV, as aUAV may be configured to launch itself. For example, a “tail sitter” UAVtypically has fixed wings to provide lift and allow the UAV to glide,but also is configured to take off and land vertically on its own. Otherexamples of self-launching UAVs are also possible.

In a further aspect, various other types of unmanned vehicles may beutilized to provide remote medical support. Such vehicles may include,for example, unmanned ground vehicles (UGVs), unmanned space vehicles(USVs), and/or unmanned underwater vehicles (UUVs). A UGV may be avehicle which is capable of sensing its own environment and navigatingsurface-based terrain without input from a driver. Examples of UGVsinclude watercraft, cars, trucks, buggies, motorcycles, treadedvehicles, and retrieval duck decoys, among others. A UUV is a vehiclethat is capable of sensing its own environment and navigating underwateron its own, such as a submersible vehicle. Other types of unmannedvehicles are possible as well.

VII. Example Components of a UAV

FIG. 7 is a simplified block diagram illustrating components of a UAV700, according to an example embodiment. UAV 700 may take the form of orbe similar in form to one of the UAVs 600, 620, 640, and 660 shown inFIGS. 6A-6D. However, UAV 700 may also take other forms.

UAV 700 may include various types of sensors, and may include acomputing system configured to provide the functionality describedherein. In the illustrated embodiment, the sensors of UAV 700 include aninertial measurement unit (IMU) 702, ultrasonic sensor(s) 704, GPS 706,imaging system(s) 708, among other possible sensors and sensing systems.The UAV 700 also includes a communication system 710, a payload deliverysystem 720, and propulsion system(s) 722.

The UAV 700 can include one or more processors 718. The processor(s) 718may include a general-purpose processor or a special purpose processor(e.g., digital signal processors, application specific integratedcircuits, etc.). The one or more processors 718 can be configured toexecute computer-readable program instructions 714 that are stored inthe data storage 712 and are executable to provide the functionality ofa UAV described herein.

The data storage 712 may include or take the form of one or morecomputer-readable storage media that can be read or accessed by at leastone processor 718. The one or more computer-readable storage media caninclude volatile and/or non-volatile storage components, such asoptical, magnetic, organic or other memory or disc storage, which can beintegrated in whole or in part with at least one of the one or moreprocessors 718. In some embodiments, the data storage 712 can beimplemented using a single physical device (e.g., one optical, magnetic,organic or other memory or disc storage unit), while in otherembodiments, the data storage 712 can be implemented using two or morephysical devices.

As noted, the data storage 712 can include computer-readable programinstructions 714 and perhaps additional data, such as diagnostic data ofthe UAV 700. The program instructions 714 may be configured to cause theUAV 700 to perform or facilitate some or all of the UAV functionalitydescribed herein. For instance, in the illustrated embodiment, programinstructions 714 include a navigation module 715 and an automateddelivery module 716. The navigation module 715 can be a set of programinstructions that, when executed by the processor(s) 718, generateflight commands to operate the propulsion system(s) 722 so as to causethe UAV 700 to navigate to a particular location and/or along aparticular flight path. The delivery module 716 can be a set of programinstructions that, when executed by the processor(s) 718, operate thepayload delivery system 720 to lower a payload to the ground and releasethe payload. The delivery module 716 may also function to cause the UAV700 to receive communication(s) from a remote operator indicative of aparticular target location at which to deliver the payload and/or anauthorization to initiate delivery and/or retraction of the payloaddelivery system 720. Other functions are also possible, includingfunctions of the UAVs and payload delivery systems described above inconnection with FIGS. 1-5.

A. Sensors

In an illustrative embodiment, IMU 702 may include both an accelerometerand a gyroscope, which may be used together to determine theorientation, position, and/or elevation of the UAV 700. In particular,the accelerometer can measure the orientation of the UAV 700 withrespect to earth, while the gyroscope measures the rate of rotationaround an axis. IMUs are commercially available in low-cost, low-powerpackages. For instance, an IMU 702 may take the form of or include aminiaturized MicroElectroMechanical System (MEMS) or aNanoElectroMechanical System (NEMS). Other types of IMUs may also beutilized.

An IMU 702 may include other sensors, in addition to accelerometers andgyroscopes, which may help to better determine position and/or help toincrease autonomy of the UAV 700. Two examples of such sensors aremagnetometers and pressure sensors. Other examples are also possible.(Note that a UAV could also include such additional sensors as separatecomponents from an IMU.)

While an accelerometer and gyroscope may be effective at determining theorientation of the UAV 700, slight errors in measurement may compoundover time and result in a more significant error. However, an exampleUAV 700 may be able mitigate or reduce such errors by using amagnetometer to measure direction. One example of a magnetometer is alow-power, digital 3-axis magnetometer, which can be used to realize anorientation independent electronic compass for accurate headinginformation based on the Earth's magnetic field. However, other types ofmagnetometers may be utilized as well.

UAV 700 may also include a pressure sensor or barometer, which can beused to determine the altitude of the UAV 700. Alternatively, othersensors, such as sonic altimeters or radar altimeters, can be used toprovide an indication of altitude, which may help to improve theaccuracy of and/or prevent drift of an IMU.

In a further aspect, UAV 700 may include one or more sensors that allowthe UAV to sense objects in the environment. For instance, in theillustrated embodiment, UAV 700 includes ultrasonic sensor(s) 704.Ultrasonic sensor(s) 704 can determine the distance to an object bygenerating sound waves and determining the time interval betweentransmission of the wave and receiving the corresponding echo off anobject. A typical application of an ultrasonic sensor for unmannedvehicles or IMUs is low-level altitude control and obstacle avoidance.An ultrasonic sensor can also be used for vehicles that need to hover ata certain height or need to be capable of detecting obstacles. Othersystems can be used to determine, sense the presence of, and/ordetermine the distance to nearby objects, such as a light detection andranging (LIDAR) system, laser detection and ranging (LADAR) system,and/or an infrared or forward-looking infrared (FLIR) system, amongother possibilities.

UAV 700 also includes a GPS receiver 706. The GPS receiver 706 may beconfigured to provide data that is typical of well-known GPS systems,such as the GPS coordinates of the UAV 700. Such GPS data may beutilized by the UAV 700 for various functions. For example, the UAV 700may use its GPS receiver 706 to help navigate to a target GPS location.In some scenarios a target GPS location may be based in part on adatabase that associates GPS coordinates with street addresses or may bebased in part on GPS coordinates obtained from a mobile device. Otherexamples are also possible.

UAV 700 may also include one or more imaging system(s) 708. For example,one or more still and/or video cameras may be utilized by a UAV 700 tocapture image data from the UAV's environment. As a specific example,charge-coupled device (CCD) cameras or complementarymetal-oxide-semiconductor (CMOS) cameras can be used with unmannedvehicles. Such imaging sensor(s) 708 have numerous possibleapplications, such as obstacle avoidance, localization techniques,ground tracking for more accurate navigation (e.g., by applying opticalflow techniques to images), video feedback, and/or image recognition andprocessing, among other possibilities.

In a further aspect, UAV 700 may use its one or more imaging system 708to help in determining location. For example, UAV 700 may captureimagery of its environment and compare it to what it expects to see inits environment given current estimated position (e.g., its current GPScoordinates), and refine its estimate of its position based on thiscomparison.

In a further aspect, UAV 700 may include one or more microphones. Suchmicrophones may be configured to capture sound from the UAVsenvironment. Other environmental sensors are also possible.

B. Navigation and Location Determination

The navigation module 715 may provide functionality that allows the UAV700 to, e.g., move about in its environment and reach a desiredlocation. To do so, the navigation module 715 may control the altitudeand/or direction of flight by controlling the mechanical features of theUAV that affect flight (e.g., rotors 602 of UAV 600).

In order to navigate the UAV 700 to a target location, a navigationmodule 715 may implement various navigation techniques, such asmap-based navigation and localization-based navigation, for instance.With map-based navigation, the UAV 700 may be provided with a map of itsenvironment, which may then be used to navigate to a particular locationon the map. With localization-based navigation, the UAV 700 may becapable of navigating in an unknown environment using localization.Localization-based navigation may involve a UAV 700 building its own mapof its environment and calculating its position within the map and/orthe position of objects in the environment. For example, as a UAV 700moves throughout its environment, the UAV 700 may continuously uselocalization to update its map of the environment. This continuousmapping process may be referred to as simultaneous localization andmapping (SLAM). Other navigation techniques may also be utilized.

In some embodiments, the navigation module 715 may navigate using atechnique that relies on waypoints. In particular, waypoints are sets ofcoordinates that identify points in physical space. For instance, anair-navigation waypoint may be defined by a certain latitude, longitude,and altitude. Accordingly, navigation module 715 may cause UAV 700 tomove from waypoint to waypoint, in order to ultimately travel to a finaldestination (e.g., a final waypoint in a sequence of waypoints).

In a further aspect, navigation module 715 and/or other components andsystems of UAV 700 may be configured for “localization” to moreprecisely navigate to the scene of a medical situation or other targetlocation. More specifically, it may be desirable in certain situationsfor a UAV to be close to the person in need of medical support (e.g.,within reach of the person), so as to properly provide medical supportto the person. To this end, the UAV 700 may use a two-tiered approach inwhich it uses a more-general location-determination technique tonavigate to a target area, and then use a more-refinedlocation-determination technique to identify and/or navigate to thetarget location within the target area.

In an alternative arrangement, a navigation module may be implemented ata remote computing device (e.g., a computing device associated with aremote operator), which communicates wirelessly with the UAV 700. Theremote computing device may receive data indicating the operationalstate of the UAV 700, sensor data from the UAV 700 that allows it toassess the environmental conditions being experienced by the UAV 700,and/or location information for the UAV 700. Provided with suchinformation, the remote computing device may determine altitudinaland/or directional adjustments that should be made by the UAV 700 and/ormay determine how the UAV should adjust its mechanical features (e.g.,rotors 602 of UAV 600) in order to effectuate such movements. The remotecomputing system may then communicate such adjustments to the UAV 700 soit can move in the determined manner. Such commands to theelectromechanical propulsion systems 722 of the UAV 700 may be referredto herein as flight-control commands, whether generated by a remotecomputing system or by the navigation module 715 on the UAV 700.

C. Payload Delivery

The payload delivery module 716 may provide functionality that allowsthe UAV 700 to autonomously or semi-autonomously lower a payload to theground and release the payload, thereby effecting delivery of thepayload on the ground. In practice, the payload delivery module 716 maybe a set of program instructions that generates commands toelectromechanical components and/or control systems of the payloaddelivery system 720 (e.g., the payload delivery system 110 of UAV 100).

The payload delivery system 720 may include aspects that selectivelysecure and release a payload (e.g., the payload-release device 106), andthat selectively lower the payload to the ground (e.g., thetether-deployment mechanism 104 and tether 102). In some cases, thepayload may be lowered to the ground using a retractable payload-releasedevice that is secured to the payload during descent and that includessensors to facilitate monitoring of the payload as it descends from theUAV 700. The payload-release device may, for example, communicateinformation from an inertial measurement unit and/or altimeter via awireless connection with the UAV 700. Data from such sensors on thepayload-release device can then be used by the payload delivery module716 to determine when the payload and/or the payload-release device havereached the ground (e.g., based on accelerometer data indicating impactwith the ground). Data from the sensors can also be used to determinewhether the payload, payload-release device, and/or tether may havebecome stuck in an obstacle such as a tree or fence, or otherwiseinterfered with by a vehicle or perhaps a pedestrian.

In addition, the payload delivery module 716 can function to cause thepayload-release assembly to ascend/descend at rates selected toencourage an intuitive, safe, and efficient interaction between thepayload delivery system and people on the ground, as described above.Additionally or alternatively, the payload delivery module 716 can causea bystander communication module to generate cues for perception bypeople on the ground during the delivery operation as described above.Other functionality of the payload delivery system 720 (and the payloaddelivery module 716) may include functions of the payload deliverysystems described above in connection with FIGS. 1-5.

D. Communication Systems

In a further aspect, UAV 700 includes one or more communication systems710. The communications systems 710 may include one or more wirelessinterfaces and/or one or more wireline interfaces, which allow UAV 700to communicate via one or more networks. Such wireless interfaces mayprovide for communication under one or more wireless communicationprotocols, such as Bluetooth, WiFi (e.g., an IEEE 802.11 protocol),Long-Term Evolution (LTE), WiMAX (e.g., an IEEE 802.16 standard), aradio-frequency ID (RFID) protocol, near-field communication (NFC),and/or other wireless communication protocols. Such wireline interfacesmay include an Ethernet interface, a Universal Serial Bus (USB)interface, or similar interface to communicate via a wire, a twistedpair of wires, a coaxial cable, an optical link, a fiber-optic link, orother physical connection to a wireline network.

In an example embodiment, a UAV 700 may include communication systems710 that allow for both short-range communication and long-rangecommunication. For example, the UAV 700 may be configured forshort-range communications using Bluetooth and for long-rangecommunications under a CDMA protocol. In such an embodiment, the UAV 700may be configured to function as a “hot spot;” or in other words, as agateway or proxy between a remote support device and one or more datanetworks, such as cellular network and/or the Internet. Configured assuch, the UAV 700 may facilitate data communications that the remotesupport device would otherwise be unable to perform by itself.

For example, UAV 700 may provide a WiFi connection to a remote device,and serve as a proxy or gateway to a cellular service provider's datanetwork, which the UAV 700 might connect to under an LTE or a 3Gprotocol, for instance. The UAV 700 could also serve as a proxy orgateway to a high-altitude balloon network, a satellite network, or acombination of these networks, among others, which a remote device mightnot be able to otherwise access.

E. Power Systems

In a further aspect, UAV 700 may include power system(s) 724. A powersystem 724 may include one or more batteries for providing power to theUAV 700. In one example, the one or more batteries may be rechargeableand each battery may be recharged via a wired connection between thebattery and a power supply and/or via a wireless charging system, suchas an inductive charging system that applies an external time-varyingmagnetic field to an internal battery.

F. Payloads

UAV 700 may employ various systems and configurations in order totransport items. In the illustrated embodiment, a payload may serve as acompartment that can hold one or more items, such that a UAV 700 candeliver the one or more items to a target delivery location. Forexample, as shown in FIG. 6A, the UAV 600 can include a compartment 608,in which an item or items may be transported. As another example, theUAV 700 can include a pick-and-place mechanism, which can pick up andhold the item while the UAV 700 is in flight, and then release the itemduring or after the UAV's descent. As yet another example, the UAV 700could include an air-bag drop system, a parachute drop system, and/or awinch system that is operable to drop or lower an item or items to adelivery location. Other examples are also possible. In someimplementations, the payload of the UAV 700 may include or take the formof a “package” designed to transport medical-support items to a targetdelivery location. For example, a medical-support UAV may include apackage with one or more items for medical support in the particularmedical situation, and/or one or more medical-support modules that aredesigned to provide medical support in the particular medical situation.In some cases, a UAV 700 may include a package that is designed for aparticular medical situation such as choking, cardiac arrest, shock,asthma, drowning, etc. In other cases, a UAV 700 may include a packagethat is designed for a number of different medical situations, which maybe associated in some way.

Such medical support items may aid in diagnosing and/or treating aperson who needs medical assistance, or may serve other purposes.Example of medical-support items include, but are not limited to: (a)medicines, (b) diagnostic devices, such as a pulse oximeter, bloodpressure sensor, or EKG sensor, (c) treatment devices, such as anEpiPen, a first aid kit, or various kinds of defibrillators (e.g., anautomated external defibrillator (AED)), and/or (d) remote supportdevices, such as a mobile phone or a head-mountable device (HMD), amongother possibilities. Note that some items that are electronic mayinclude one or more batteries to provide power to the item. Thesebatteries may be rechargeable and may be recharged using one or morewired or wireless charging systems. In addition or on in thealternative, an item may be integrated with one or more batteries in thepower system 724 for power.

In some embodiments, UAV 700 could include an integrated system ordevice for administering or assisting in the administration of medicalcare (e.g., a system or device having one or more components that arebuilt in to the structure of the UAV itself). For example, as notedabove, a UAV could include an oxygen-therapy system. In an exampleconfiguration, an oxygen-therapy system might include a mask that isconnected via tubing to an on-board oxygen source. Configured as such,the UAV could release the oxygen mask when it reaches a person in needof oxygen (e.g., at a fire scene).

As another example of a UAV with an integrated medical-support device,UAV 700 might function as a mobile defibrillator. Specifically, ratherthan carry a stand-alone defibrillator that can then be removed from theUAV for use, the UAV itself may function as a defibrillator.

G. Service Modules

As noted above, UAV 700 may include one or more service modules. The oneor more service modules may include software, firmware, and/or hardwarethat may help to provide or assist in the provision of the UAV-relatedservices. In some examples, the one or more service modules describedherein may be implemented, at least in part, by the program instructions714 configured to be executed by the processor(s) 718.

Configured as such, a UAV 700 may provide various types of service. Forinstance, the UAV 700 may have stored information that can be providedto a person or persons at the target location, in order to assist theperson or persons in various ways. For example, the UAV 700 may includea video or audio file with instructions for performing some task, whichthe UAV 700 can play out to a person at the target location. As anotherexample, the UAV 700 may include an interactive program to assist aperson at the target location in performing some task. For instance, theUAV 700 may include an application that analyzes the person's speech todetect questions related to the medical situation and/or that provides atext-based interface via which the person can ask such questions, andthen determines and provides answers to such questions.

In some embodiments, UAV 700 may facilitate communication between alayperson and/or medical personnel at the scene and medical personnel ata remote location. As an example, a service module may provide a userinterface via which a person at the scene can use a communication system710 of the UAV to communicate with an emergency medical technician at aremote location. As another example, the UAV 700 can unlock certaincapabilities of a remote device, such as a mobile phone, which is nearthe UAV 700 at the scene of a medical situation. Such capabilities maybe inaccessible to a user of the remote device, unless the remote deviceis within a certain distance from the UAV 700 such that the UAV 700 canunlock the capabilities. For example, the UAV 700 may send the remotedevice a security key that allows the remote device to establish asecure connection to communicate with medical personnel at a remotelocation. Other examples are also possible.

VIII. Example UAV Systems

UAV systems may be implemented in order to provide various services. Inparticular, UAVs may be provided at a number of different launch sites,which may be in communication with regional and/or central controlsystems. Such a distributed UAV system may allow UAVs to be quicklydeployed to provide services across a large geographic area (e.g., thatis much larger than the flight range of any single UAV). For example,UAVs capable of carrying payloads may be distributed at a number oflaunch sites across a large geographic area (possibly even throughout anentire country, or even worldwide), in order to deliver various items tolocations throughout the geographic area. As another example, adistributed UAV system may be provided in order to provide remotemedical support, via UAVs. FIG. 8 is a simplified block diagramillustrating a distributed UAV system 800, according to an exampleembodiment.

In an example UAV system 800, an access system 802 may allow forinteraction with, control of, and/or utilization of a network of UAVs804. In some embodiments, an access system 802 may be a computing systemthat allows for human-controlled dispatch of UAVs 804. As such, thecontrol system may include or otherwise provide a user interface (UI)803 via which a user can access and/or control UAVs 804. In someembodiments, dispatch of UAVs 804 may additionally or alternatively beaccomplished via one or more automated processes. The access system 802and associated UI 803 that allow for human-controlled dispatch may beimplemented, for example, using a remote terminal for supervisorycontrol that provides information to a human operator (e.g., a videostream from one of the UAVs 804), and receives an input from the remoteoperator to indicate an action to be performed by the UAV 804.

Further, the access system 802 may provide for remote operation of aUAV. For instance, an access system 802 may allow an operator to controlthe flight of a UAV 804 via user interface 803. As a specific example,an operator may use an access system to dispatch a UAV 804 to deliver apackage to a target location. The UAV 804 may then autonomously navigateto the general area of the target location. At this point, the operatormay use the access system 802 to take over control of the UAV 804, andnavigate the UAV to the target location (e.g., to a particular person towhom a payload is being sent). Other examples of remote operation of theUAV 804 are also possible.

The UAVs 804 may take various forms. For example, each UAV 804 may be aUAV such as those illustrated in FIGS. 6A-6D. However, UAV system 800may also utilize other types of UAVs without departing from the scope ofthe present disclosure. In some implementations, all UAVs 804 may be ofthe same or a similar configuration. However, in other implementations,UAVs 804 may include a number of different types of UAVs. For instance,UAVs 804 may include a number of types of UAVs, with each type of UAVbeing configured for a different type or types of medical support.

A remote device 806 may take various forms. Generally, a remote device806 may be any device via which a direct or indirect request to dispatchUAV 804 can be made. (Note that an indirect request may involve anycommunication that may be responded to by dispatching a UAV; e.g.,requesting a payload delivery). In an example embodiment, a remotedevice 806 may be a mobile phone, tablet computer, laptop computer,personal computer, or any network-connected computing device. Further,in some instances, remote device 806 may not be a computing device. Asan example, a standard telephone, which allows for communication viaplain old telephone service (POTS), may serve as a remote device 806.Other types of remote devices are also possible.

Further, a remote device 806 may be configured to communicate withaccess system 802 via one or more types of communication network(s). Forexample, a remote device 806 could communicate with access system 802(or via a human operator of the access system) by placing a phone callover a POTS network, a cellular network, and/or a data network such asthe Internet. Other types of networks may also be utilized.

In some embodiments, a remote device 806 may be configured to allow auser to request delivery of one or more items to a desired location. Forexample, a user could request UAV delivery of a payload to their homevia their mobile phone, tablet, or laptop. As another example, a usercould request dynamic delivery to whatever location they are at the timeof delivery. To provide such dynamic delivery, the UAV system 800 mayreceive location information (e.g., GPS coordinates, etc.) from theuser's mobile phone, or any other device on the user's person, such thatthe UAV 804 can navigate to the user's location (as indicated by theirmobile phone).

In an example arrangement, central dispatch system 808 may be a serveror group of servers, which is configured to receive dispatch messagesrequests and/or dispatch instructions from an access system 802. Suchdispatch messages may request or instruct the central dispatch system808 to coordinate the deployment of UAVs to various target locations. Acentral dispatch system 808 may be further configured to route suchrequests or instructions to local dispatch systems 810. To provide suchfunctionality, central dispatch system 808 may communicate with accesssystem 802 via a data network, such as the Internet or a private networkthat is established for communications between access systems andautomated dispatch systems.

In the illustrated configuration, central dispatch system 808 may beconfigured to coordinate the dispatch of UAVs 804 from a number ofdifferent local dispatch systems 810. As such, central dispatch system808 may keep track of which UAVs 804 are located at which local dispatchsystems 810, which UAVs 804 are currently available for deployment,and/or which services or operations each of the UAVs 804 is configuredfor (in the event that a UAV fleet includes multiple types of UAVsconfigured for different services and/or operations). Additionally oralternatively, each local dispatch system 810 may be configured to trackwhich of its associated UAVs 804 are currently available for deploymentand/or which services or operations each of its associated UAVs isconfigured for.

In some cases, when central dispatch system 808 receives a request forUAV-related service from an access system 802, central dispatch system808 may select a specific UAV 804 to dispatch. The central dispatchsystem 808 may accordingly instruct the local dispatch system 810 thatis associated with the selected UAV to dispatch the selected UAV. Thelocal dispatch system 810 may then operate its associated deploymentsystem 812 to launch the selected UAV. In other cases, a centraldispatch system 808 may forward a request for a UAV-related service to alocal dispatch system 810 that is near the location where the support isrequested, and leave the selection of a particular UAV 804 to the localdispatch system 810.

In an example configuration, a local dispatch system 810 may beimplemented in a computing system at the same location as the deploymentsystem or systems 812 that it controls. For example, in someembodiments, a local dispatch system 810 could be implemented by acomputing system at a building where the deployment systems 812 and UAVs804 that are associated with the particular local dispatch system 810are also located. In other embodiments, a local dispatch system 810could be implemented at a location that is remote to its associateddeployment systems 812 and UAVs 804.

Numerous variations on and alternatives to the illustrated configurationof UAV system 800 are possible. For example, in some embodiments, a userof a remote device 806 could request medical support directly from acentral dispatch system 808. To do so, an application may be implementedon a remote device 806 that allows the user to provide informationregarding a requested service, and generate and send a data message torequest that the UAV system provide the service. In such an embodiment,central dispatch system 808 may include automated functionality tohandle requests that are generated by such an application, evaluate suchrequests, and, if appropriate, coordinate with an appropriate localdispatch system 810 to deploy a UAV.

Further, in some implementations, some or all of the functionality thatis attributed herein to central dispatch system 808, local dispatchsystem(s) 810, access system 802, and/or deployment system(s) 812 couldbe combined in a single system, implemented in a more complex system,and/or redistributed among central dispatch system 808, local dispatchsystem(s) 810, access system 802, and/or deployment system(s) 812 invarious ways.

Yet further, while each local dispatch system 810 is shown as having twoassociated deployment systems, a given local dispatch system 810 mayhave more or less associated deployment systems. Similarly, whilecentral dispatch system 808 is shown as being in communication with twolocal dispatch systems 810, a central dispatch system may be incommunication with more or less local dispatch systems 810.

In a further aspect, a deployment system 812 may take various forms. Ingeneral, a deployment system may take the form of or include a systemfor physically launching a UAV 804. Such a launch system may includefeatures that allow for a human-assisted UAV launch and/or features thatprovide for an automated UAV launch. Further, a deployment system 812may be configured to launch one particular UAV 804, or to launchmultiple UAVs 804.

A deployment system 812 may further be configured to provide additionalfunctions, including for example, diagnostic-related functions such asverifying system functionality of the UAV, verifying functionality ofdevices that are housed within a UAV (e.g., such as a defibrillator, amobile phone, or an HMD), and/or maintaining devices or other items thatare housed in the UAV (e.g., by charging a defibrillator, mobile phone,or HIVID, or by checking that medicine has not expired).

In some embodiments, the deployment systems 812 and their correspondingUAVs 804 (and possibly associated local dispatch systems 810) may bestrategically distributed throughout an area such as a city. Forexample, deployment systems 812 may be located on the roofs of certainmunicipal buildings, such as fire stations, which can thus serve as thedispatch locations for UAVs 704. Fire stations may function well fordispatch of emergency response UAVs (e.g., UAVs used to deliveryemergency medical supplies, relief items, or interactive equipment toassist people in responding to an emergency situation). Fire stationstend to be distributed well with respect to population density, theirroofs tend to be flat, and the use of firehouse roofs as leased spacesfor dispatch of emergency response UAVs could further the public good.However, deployment systems 812 (and possibly the local dispatch systems810) may be distributed in other ways, depending upon the particularimplementation. As an additional example, kiosks that allow users totransport packages via UAVs may be installed in various locations. Suchkiosks may include UAV launch systems, and may allow a user to providetheir package for loading onto a UAV and pay for UAV shipping services,among other possibilities. Other examples are also possible.

In a further aspect, a UAV system 800 may include or have access to auser-account database 814. The user-account database 814 may includedata for a number of user-accounts, which are each associated with oneor more persons. For a given user-account, the user-account database 814may include data related to or useful in providing UAV-related services.Typically, the user data associated with each user-account is optionallyprovided by an associated user and/or is collected with the associateduser's permission.

Further, in some embodiments, a person may have to register for auser-account with the UAV system 800 in order to use or be provided withUAV-related services by the UAVs 804 of UAV system 800. As such, theuser-account database 814 may include authorization information for agiven user-account (e.g., a user-name and password), and/or otherinformation that may be used to authorize access to a user-account.

In some embodiments, a person may associate one or more of their deviceswith their user-account, such that they can be provided with access tothe services of UAV system 800. For example, when a person uses anassociated mobile phone, e.g., to place a call to an operator of accesssystem 802 or to send a message requesting a UAV-related service to adispatch system, the phone may be identified via a unique deviceidentification number, and the call or message may then be attributed tothe associated user-account. Other examples are also possible.

In some examples, an individual user or a group of users may create adata-based “user-account,” which may also be referred to simply as an“account.” A user-account for a particular user or user group mayinclude data related to the particular user or user group, which theuser or user group has opted to provide for the user-account. As such, aparticular user's account may, in a sense, be a data-basedrepresentation of that particular user. A user may create an account forvarious applications, web sites, and/or online services, for instance.Examples of user accounts include e-mail accounts, social networkaccounts, online financial accounts, accounts with service providers,among other possibilities. Further, in some cases, a user may have asingle user-account that provides as a data-based representation of theuser for multiple services, websites, applications, etc. For instance, auser could opt to use their e-mail account or social network account asa common login for various online services and applications, which areprovided by a number of different entities. Further, a user of acomputing device, such as a mobile phone, laptop computer, or wearablecomputing device, may associate their user-account with the computingdevice itself, such that while the user is operating the computingdevice, their account will be associated with applications that areprovided on the computing device.

In situations in which the systems discussed here collect personalinformation about users, or may make use of personal information, theusers may be provided with an opportunity to control whether programs orfeatures collect user information (e.g., information about a user'ssocial network, social actions or activities, profession, a user'spreferences, or a user's current location), or to control whether and/orhow to receive content from the content serer that may be more relevantto the user. In addition, certain data may be treated in one or moreways before it is stored or used, so that personally identifiableinformation is removed. For example, a user's identity may be treated sothat no personally identifiable information can be determined for theuser, or a user's geographic location may be generalized where locationinformation is obtained (such as to a city, ZIP code, or state level),so that a particular location of a user cannot be determined. Thus, theuser may haw control over how information is collected about the userand used by a content server.

IX. Conclusion

Where example embodiments involve information related to a person or adevice of a person, the embodiments should be understood to includeprivacy controls. Such privacy controls include, at least, anonymizationof device identifiers, transparency and user controls, includingfunctionality that would enable users to modify or delete informationrelating to the user's use of a product.

The particular arrangements shown in the Figures should not be viewed aslimiting. It should be understood that other embodiments may includemore or less of each element shown in a given Figure. Further, some ofthe illustrated elements may be combined or omitted. Yet further, anexemplary embodiment may include elements that are not illustrated inthe Figures.

Additionally, while various aspects and embodiments have been disclosedherein, other aspects and embodiments will be apparent to those skilledin the art. The various aspects and embodiments disclosed herein are forpurposes of illustration and are not intended to be limiting, with thetrue scope and spirit being indicated by the following claims. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which arecontemplated herein.

What is claimed is:
 1. A system comprising: a payload having a lightsource arranged thereon; a tether coupled to an unmanned aerial vehicle(UAV), wherein the tether suspends the payload below the UAV, andwherein the payload is configured to releasably couple to the tether; aretraction system operable to use the tether to lower the payload fromthe UAV; an imaging system arranged on the UAV such that while thepayload is suspended from the UAV via the tether, the imaging systemdetects light emitted from the light source on the payload; and acontrol system configured to: (i) while the payload is suspended fromthe UAV via the tether, receive image data from the imaging system; (ii)identify, based on the received image data, an image coordinateassociated with the light source situated on the payload; (iii)determine a position of the payload based at least in part on theidentified image coordinate; (iv) determine, based at least in part onthe position of the payload, flight-control commands to move the UAV soas to cause the payload to become closer to a path of descent associatedwith a delivery location; and (v) cause the UAV to operate in accordancewith the determined flight-control commands.
 2. The system of claim 1,wherein the control system is further configured to: while the UAVhovers over a delivery location, use the retraction system to initiate adelivery operation, wherein initiating the delivery operation compriseslowering the payload secured thereby toward the ground such that thepayload descends from the UAV; determine that the payload is at or nearthe ground; and in response to determining that the payload is at ornear the ground, release the payload.
 3. The system of claim 2, whereinthe control system is further configured to: determine that thedetermined position of the payload is within a threshold distance of thedelivery location; and cause the release of the payload in response toboth determining that the payload is at or near the ground and that thedetermined position of the payload is within the threshold distance ofthe delivery location.
 4. The system of claim 1, wherein the controlsystem is further configured to: determine, based at least in part onthe determined position of the payload, flight-control commands tonavigate the UAV, in hover mode, so as to cause the suspended payload tobecome closer to a path of descent associated with a delivery location;and cause the UAV to fly, in hover mode, in accordance with thedetermined flight-control commands.
 5. The system of claim 4, whereinthe control system is further configured to: prior to causing the UAV tofly, in hover mode, in accordance with the determined flight-controlcommands, determine that the determined position of the payload isgreater than a threshold distance from the path of descent associatedwith the target delivery location.
 6. The system of claim 4, wherein thecontrol system determining the flight-control commands comprises thecontrol system: (a) determining a translational offset of the UAV whichcompensates for a displacement between the determined position of thepayload and the path of descent associated with the target deliverylocation, wherein the translational offset is based on: the identifiedimage coordinate associated with the light source, an image coordinateassociated with the path of descent, and a current elevation of the UAV,and (b) using a navigational module to determine the flight-controlcommands which cause the UAV to traverse the determined translationaloffset in hover mode.
 7. The system of claim 1, wherein the imagingsystem comprises a downward-facing camera mounted to the UAV via agimbal mount so as to substantially maintain an orientation of the pointof view of the camera.
 8. The system of claim 1, wherein the lightsource is a first light source and a second light source is alsosituated on the payload such that, while the payload is suspended fromthe UAV via the tether, both the first and second light sources arearranged to emit light toward the UAV, and wherein the control system isfurther configured to: identify a pattern in the received image datathat corresponds to light received from both the first and second lightsources; identify, in the pattern, respective image coordinatesassociated with the first and second light sources, and determine theposition of the payload based at least in part on both the imagecoordinate associated with the first light source and the imagecoordinate associated with the second light source.
 9. The system ofclaim 8, wherein the first light source is configured to emit lighthaving a first wavelength and the second light source is configured toemit light having a second wavelength different from the firstwavelength.
 10. The system of claim 8, wherein the first and secondlight sources are situated at respective positions on the payload, andwherein the control system identifying the pattern within the receivedimage data comprises the control system identifying a pattern in whichlight from the first and second light sources are received fromrespective emission locations that are spatially separated from oneanother.
 11. The system of claim 10, wherein the control system isfurther configured to determine an orientation of the payload while thepayload is suspended from the UAV based on the image coordinatesassociated with the first and second light sources.
 12. The system ofclaim 1, wherein the light source is configured to emit light having acharacteristic modulation towards the UAV, and wherein the controlsystem is further configured to use the characteristic modulation todistinguish light from the light source from background light.
 13. Thesystem of claim 1, wherein the light source comprises a light emittingdiode that emits infrared or near-infrared light.
 14. A methodcomprising: while a payload is suspended from an unmanned aerial vehicle(UAV) via a tether, receiving image data from an imaging sensor system,wherein the imaging sensor system comprises an image sensor mounted onthe UAV such that, while the payload is suspended from the UAV via thetether, a field of view of the image sensor includes a light source thatis situated on the payload and arranged to emit light toward the UAV;identifying, by a computing system, based on the received image data, animage coordinate associated with the light source situated on thepayload; determining, by the computing system, based at least in part onthe identified image coordinate, a position of the payload; determining,by the computing system, based at least in part on the position of thepayload, flight-control commands to navigate the UAV, such that movementof the UAV causes the suspended payload to become closer to a path ofdescent associated with a delivery location; and causing, by thecomputing system the UAV to fly, in accordance with the determinedflight-control commands.
 15. The method of claim 14, wherein the payloadis configured to be releasably coupled to the tether, the method furthercomprising: while the UAV hovers over a delivery location, using aretractable delivery system to initiate a delivery operation, whereininitiating the delivery operation comprises lowering the payload towardthe ground such that the payload descends from the UAV; determining thatthe payload is at or near the ground; determining that the determinedposition of the payload is within a threshold distance of the deliverylocation; and causing the payload to be released in response to bothdetermining that the payload is at or near the ground and that thedetermined position of the payload is within the threshold distance ofthe delivery location.
 16. The method of claim 14, further comprising:determining, based at least in part on the determined position of thepayload, flight-control commands to navigate the UAV, in hover mode, soas to cause the payload to become closer to a path of descent associatedwith a delivery location; and causing the UAV to fly, in hover mode, inaccordance with the determined flight-control commands.
 17. The methodof claim 16, wherein determining the flight-control commands comprises:determining a translational offset of the UAV which compensates for adisplacement between the determined position of the payload and the pathof descent associated with the delivery location, wherein thetranslational offset is based on: the identified image coordinateassociated with the light source, an image coordinate associated withthe path of descent, and a current elevation of the UAV; and using anavigational module to determine the flight-control commands which causethe UAV to traverse the determined translational offset in hover mode.